Q: Freeze after updating to OSX Snow Leopard and version 10.6.8

Not enough details. Provide computer, what you're doing, and what happens. Freezing doesn't tell us much.

I have a similar problem. iMac 2008 recently updated to 10.6.8 from 10.5. UI freezes about once per day requiring a hard restart. Sometimes the screen goes blue, sometimes black and sometimes whatever app was running is displayed but is frozen. Strangely the mouse pointer may be active but the UI is otherwise unresponsive. We thought it was a Safari issue, but it happened yesterday when Safari wasn't running. Computer not used for really intensive tasks.

System ran fine prior to upgrading the OS. Software update is current. No new hardware or modifications.

Step by Step to fix your Mac

I have been working through the list of actions and I believe I have identified an issue repairing permissions. I ran Disk Utility from the HD and it reported several issues and that they were repaired. I repeated the repair and the same thing happened. I repeated several times expecting to eventually have the utility report that no repairs were needed. Instead, it kept reporting apparently the same permissions problems and that they have been fixed.

I next tried booting off the install DVD and repeating above. Same result. How do I remedy disk permissions issues that won't stay repaired?

I will look around the forums, but wanted to report an update.

The repairs filled about six pages of a Word file; here are a few samples of what is reported:

Repairing permissions for “20 inch iMac HD”

Permissions differ on "System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/dt.jar", should be lrwxr-xr-x , they are lrw-r--r-- .

Repaired "System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/dt.jar".

Permissions differ on "System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/jce.jar", should be lrwxr-xr-x , they are lrw-r--r-- .

Repaired "System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/jce.jar".

Permissions differ on "System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/jconsole.ja r", should be lrwxr-xr-x , they are lrw-r--r-- .

Repaired "System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/jconsole.ja r".

Permissions differ on "System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/management- agent.jar", should be lrwxr-xr-x , they are lrw-r--r-- .

<continue for six pages....>

"System/Library/CoreServices/RemoteManagement/AppleVNCServer.bundle/Contents/Sup port/LockScreenLeopard386.app/Contents/Resources/English.lproj/MainMenu.nib", should be drwxr-xr-x , they are -rwxr-xr-x .

Repaired "System/Library/CoreServices/RemoteManagement/AppleVNCServer.bundle/Contents/Su pport/LockScreenLeopard386.app/Contents/Resources/English.lproj/MainMenu.nib".

Permissions repair complete

WRT repairing permissions in SL, http://support.apple.com/kb/TS1448 says that "You can safely ignore these messages. You can also usually ignore any "ACL found but not expected..." message." Do note that DU's repair facility fails when dealing with symbolic links. So, just ignore after repairing one time.

I have been working through the step by step troubleshooting without success. This past week I performed a clean install of 10.6.8 on a USB external HD and booted from this disk. This was a stripped down system, I did not migrate any files or the user account from the internal drive.

While running this basic system, I ejected the internal drive and just ran off the external. To be clear: new user account, no music, Safari favorites, added applications (that didn't install from the DVD), plug ins or files of any kind. This HD had hundreds of GB of available space. Still froze. This makes me think I can rule out the internal HD having a mechanical failure, wonky applications or corrupted file stucture on that internal drive because it was ejected.

I have now gone back to using the internal HD and I upgraded to OS 10.8.2 and the problem persists. AHT has been run three times. The first time was three weeks ago and no problems reported. Ran again today and an error was reported for a Firewire HD. I do use a FW drive for Time Machine backups. Note that this is an entirely different drive than the one I had made bootable. I disconnected this drive and repeated the test and no problems were reported. Despite these results, I now strongly suspect an undetected hardware problem, but what is it?

I do have the iStat widget and I commonly see temperatures for GPU, diode and heatsink ~ 130 - 140 deg C each which seems high to me. I cannot find a reference for what is appropriate.