My Early 2008 iMac freeze with no apparent reason

I have an Early 2008 iMac (2.66GHz Core 2 Duo with 4GB RAM).

Since installing Lion, sometimes the computer freezes without apparent reason.

The only thing I'm sure is that this is NOT the same as the Quicktime video problem – I wasn't watching a Quicktime video, nor a Flash website when it froze. Actually, today happened while I wasnt' doing anything: the computer was on, but I was at launch.

Anyway, what happens is really strange: the screen freeze, I can't do things like change volume, but the mouse still works – albeit without producing results on screen such as dock magnification etc. Also, while the computer was frozen a Time Machine backup occured as scheduled, and I was able to stream my computer's music to my iPhone using the Home Sharing feature.

The clock also remain frozen (at 12:51), so I looked at the logs and this is what I found:

11/01/12 12:46:42,783 iTunes: _NotificationSocketReadCallbackGCD (thread 0x7fff73778960): Unexpected connection closure...

11/01/12 12:55:58,614 com.apple.usbmuxd: _SendAttachNotification (thread 0x7fff73778960): sending attach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _GetAddrInfoReplyReceivedCallback matched.

11/01/12 12:55:58,898 usbmuxd: _AMDeviceConnectByAddressAndPort (thread 0x101281000): IPv4

11/01/12 12:55:59,072 ath: _AMDDeviceAttachedCallbackv3 (thread 0x7fff73778960): Device 'AMDevice 0x10185aa80 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 33, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 12:55:59,072 iTunes: _AMDDeviceAttachedCallbackv3 (thread 0x10fced000): Device 'AMDevice 0x7f9122ee51f0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 33, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 12:56:00,758 AppleMobileDeviceHelper: _AMDDeviceDetached (thread 0xacbba2c0): Device 'AMDevice 0x52ea00 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 32, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 12:56:01,682 AppleMobileDeviceHelper: _AMDDeviceAttachedCallbackv3 (thread 0xacbba2c0): Device 'AMDevice 0x33b210 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 33, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 12:56:34,322 com.apple.usbmuxd: _SendDetachNotification (thread 0x7fff73778960): sending detach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _BrowseReplyReceivedCallback got bonjour removal.

11/01/12 12:56:34,322 iTunes: _AMDDeviceDetached (thread 0x10fced000): Device 'AMDevice 0x7f9122ee51f0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 33, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 12:56:34,324 iTunes: _NotificationSocketReadCallbackGCD (thread 0x7fff73778960): Unexpected connection closure...

11/01/12 13:00:22,505 com.apple.usbmuxd: _SendAttachNotification (thread 0x7fff73778960): sending attach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _GetAddrInfoReplyReceivedCallback matched.

11/01/12 13:00:22,974 usbmuxd: _AMDeviceConnectByAddressAndPort (thread 0x100781000): IPv4

11/01/12 13:00:23,344 iTunes: _AMDDeviceAttachedCallbackv3 (thread 0x10fced000): Device 'AMDevice 0x7f9123cc9db0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 34, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:00:23,344 ath: _AMDDeviceAttachedCallbackv3 (thread 0x7fff73778960): Device 'AMDevice 0x10186ccf0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 34, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:00:25,583 AppleMobileDeviceHelper: _AMDDeviceDetached (thread 0xacbba2c0): Device 'AMDevice 0x33b210 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 33, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 13:00:26,228 AppleMobileDeviceHelper: _AMDDeviceAttachedCallbackv3 (thread 0xacbba2c0): Device 'AMDevice 0x549be0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 34, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:01:51,000 kernel: ** Device in slot: SLOT--1 **

11/01/12 13:01:51,000 kernel: ** GPU Debug Info Start **

11/01/12 13:01:51,000 kernel: 0x00009583

11/01/12 13:01:51,000 kernel: 0x000000d6

11/01/12 13:01:51,000 kernel: 0x00000001

11/01/12 13:01:51,000 kernel: 0x00000018

11/01/12 13:01:51,000 kernel: 0x0000d052

11/01/12 13:01:51,000 kernel: 0x00000001

11/01/12 13:01:51,000 kernel: 0x00000001

11/01/12 13:01:51,000 kernel: 0x00009583

11/01/12 13:01:51,000 kernel: 0x00000001

11/01/12 13:01:51,000 kernel: 0x00000015

11/01/12 13:01:51,000 kernel: 0x00000000

11/01/12 13:01:51,000 kernel: 0x00000001

It goes on like this for a while, then:

11/01/12 13:02:10,000 kernel: 0xffffffff

11/01/12 13:02:10,000 kernel: 0xffffffff

11/01/12 13:02:10,000 kernel: 0xffffffff

11/01/12 13:02:10,000 kernel: 0xffffffff

11/01/12 13:02:10,000 kernel: 0xffffffff

11/01/12 13:02:10,000 kernel: 0xc0016900

11/01/12 13:02:10,000 kernel: 0x000001b1

11/01/12 13:02:10,000 kernel: 0x00000004

11/01/12 13:02:10,000 kernel: 0xc0016900

11/01/12 13:02:10,000 kernel: 0x00000207

11/01/12 13:02:10,000 kernel: ** GPU Debug Info End **

11/01/12 13:05:56,965 com.apple.usbmuxd: _SendDetachNotification (thread 0x7fff73778960): sending detach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _BrowseReplyReceivedCallback got bonjour removal.

11/01/12 13:05:56,966 iTunes: _AMDDeviceDetached (thread 0x10fced000): Device 'AMDevice 0x7f9123cc9db0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 34, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 13:05:56,967 iTunes: _NotificationSocketReadCallbackGCD (thread 0x7fff73778960): Unexpected connection closure...

11/01/12 13:07:21,408 com.apple.usbmuxd: _SendAttachNotification (thread 0x7fff73778960): sending attach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _GetAddrInfoReplyReceivedCallback matched.

11/01/12 13:07:21,877 usbmuxd: _AMDeviceConnectByAddressAndPort (thread 0x100781000): IPv4

11/01/12 13:07:22,308 iTunes: _AMDDeviceAttachedCallbackv3 (thread 0x10fced000): Device 'AMDevice 0x7f9123a21160 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 35, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:07:22,308 ath: _AMDDeviceAttachedCallbackv3 (thread 0x7fff73778960): Device 'AMDevice 0x10185aa80 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 35, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:07:26,592 AppleMobileDeviceHelper: _AMDDeviceDetached (thread 0xacbba2c0): Device 'AMDevice 0x549be0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 34, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 13:07:27,131 AppleMobileDeviceHelper: _AMDDeviceAttachedCallbackv3 (thread 0xacbba2c0): Device 'AMDevice 0x362950 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 35, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:16:39,785 com.apple.backupd: Starting standard backup

11/01/12 13:16:40,019 com.apple.backupd: Backing up to: /Volumes/Backup di Time Machine/Backups.backupdb

11/01/12 13:17:14,751 com.apple.backupd: 2.43 GB required (including padding), 16.27 GB available

11/01/12 13:17:30,700 mdworker: Unable to talk to lsboxd

11/01/12 13:19:01,344 com.apple.backupd: Copied 4087 files (381.2 MB) from volume Macintosh HD.

11/01/12 13:19:11,801 com.apple.backupd: 2.27 GB required (including padding), 15.89 GB available

11/01/12 13:20:14,819 com.apple.backupd: Copied 3098 files (230.8 MB) from volume Macintosh HD.

11/01/12 13:20:23,700 mds: (Error) Volume: Could not find requested backup type:2 for volume

11/01/12 13:20:24,205 com.apple.backupd: Starting post-backup thinning

11/01/12 13:20:37,674 com.apple.backupd: Deleted /Volumes/Backup di Time Machine/Backups.backupdb/Galactica/2012-01-10-123033 (146.3 MB)

11/01/12 13:20:37,674 com.apple.backupd: Post-back up thinning complete: 1 expired backups removed

11/01/12 13:20:37,800 com.apple.backupd: Backup completed successfully.

11/01/12 13:55:00,567 com.apple.usbmuxd: _SendDetachNotification (thread 0x7fff73778960): sending detach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _BrowseReplyReceivedCallback got bonjour removal.

11/01/12 13:55:00,568 iTunes: _AMDDeviceDetached (thread 0x10fced000): Device 'AMDevice 0x7f9123a21160 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 35, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 13:55:00,569 iTunes: _NotificationSocketReadCallbackGCD (thread 0x7fff73778960): Unexpected connection closure...

11/01/12 13:57:12,071 com.apple.usbmuxd: _SendAttachNotification (thread 0x7fff73778960): sending attach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _GetAddrInfoReplyReceivedCallback matched.

11/01/12 13:57:12,379 usbmuxd: _AMDeviceConnectByAddressAndPort (thread 0x100781000): IPv4

11/01/12 13:57:12,550 iTunes: _AMDDeviceAttachedCallbackv3 (thread 0x10fced000): Device 'AMDevice 0x7f9123c28390 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 36, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:57:12,550 ath: _AMDDeviceAttachedCallbackv3 (thread 0x7fff73778960): Device 'AMDevice 0x10186ccf0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 36, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:57:14,574 AppleMobileDeviceHelper: _AMDDeviceDetached (thread 0xacbba2c0): Device 'AMDevice 0x362950 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 35, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 13:57:14,815 AppleMobileDeviceHelper: _AMDDeviceAttachedCallbackv3 (thread 0xacbba2c0): Device 'AMDevice 0x37d1d0 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 36, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 13:57:35,961 com.apple.usbmuxd: _SendDetachNotification (thread 0x7fff73778960): sending detach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _BrowseReplyReceivedCallback got bonjour removal.

11/01/12 13:57:35,961 iTunes: _AMDDeviceDetached (thread 0x10fced000): Device 'AMDevice 0x7f9123c28390 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 36, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' detached.

11/01/12 13:57:35,962 iTunes: _NotificationSocketReadCallbackGCD (thread 0x7fff73778960): Unexpected connection closure...

11/01/12 14:05:14,778 com.apple.usbmuxd: _SendAttachNotification (thread 0x7fff73778960): sending attach for device 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.: _GetAddrInfoReplyReceivedCallback matched.

11/01/12 14:05:15,177 usbmuxd: _AMDeviceConnectByAddressAndPort (thread 0x100781000): IPv4

11/01/12 14:05:15,342 ath: _AMDDeviceAttachedCallbackv3 (thread 0x7fff73778960): Device 'AMDevice 0x10185aa80 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 37, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

11/01/12 14:05:15,342 iTunes: _AMDDeviceAttachedCallbackv3 (thread 0x10fced000): Device 'AMDevice 0x7f9122fad930 {UDID = 8851d03d087cdedc1ee4cd34f58d63e07cd164e8, device ID = 37, FullServiceName = 00:26:bb:fc:33:cf@fe80::226:bbff:fefc:33cf._apple-mobdev._tcp.local.}' attached.

At this point I restarted the computer using the power button.

For the record, a few months ago I replaced the hard drive thinking it could be the problem – good thing I needed more space anyway because it happened twice AFTER I replaced it.

Any help?