Thanks, The Hatter. I'm working through all the links you've provided and see if I can narrow down the problem.
And, Grant, thanks as well-- I really appreciate the specific information. You've enabled me to track down the panic log -- but they are indeed baffling. I'm pasting one below, in case somebody wiser than I can interpret it for me.
Wed Mar 6 11:25:26 2013
panic(cpu 2 caller 0x2ceabf): Kernel trap at 0x00baf978, type 14=page fault, registers:
CR0: 0x8001003b, CR2: 0x8da19000, CR3: 0x00100000, CR4: 0x00000660
EAX: 0x7db19000, EBX: 0x07eb6004, ECX: 0x0ff00000, EDX: 0x0ff00000
CR2: 0x8da19000, EBP: 0x4469bc38, ESI: 0x0ff00000, EDI: 0x08feab04
EFL: 0x00010206, EIP: 0x00baf978, CS: 0x00000008, DS: 0x00000010
Error code: 0x00000000
Backtrace (CPU 2), Frame : Return Address (4 potential args on stack)
0x4469ba98 : 0x2203de (0x6b08cc 0x4469bab8 0x229fb0 0x0)
0x4469bac8 : 0x2ceabf (0x6bd9e0 0xbaf978 0xe 0x6bd989)
0x4469bb78 : 0x2e5564 (0x4469bba0 0x4469bb88 0x4469bb98 0x22cbbb)
0x4469bb98 : 0xbaf978 (0xe 0x44690048 0xff1b0010 0x10)
0x4469bc38 : 0x1547167 (0x8ad2c04 0x7eb6004 0xff00000 0x7eb6004)
0x4469bc58 : 0x153e35c (0x7eb6004 0x8feab04 0x0 0xff00000)
0x4469bc88 : 0xcb6c56 (0x7eb6004 0x9465004 0x4469bca0 0x0)
0x4469bd38 : 0xd27c8a (0x7eb6004 0x9465004 0x8971c14 0xff)
0x4469bdc8 : 0xd2933e (0x7eb6004 0x8a97c04 0x0 0x0)
0x4469be28 : 0xd2b46a (0x7eb6004 0x8a97c04 0x8 0x2)
0x4469be58 : 0x1562269 (0x7eb6004 0x8a97c04 0x0 0x0)
0x4469be88 : 0xd2b589 (0x7eb6004 0x8a97c04 0x0 0x0)
0x4469bed8 : 0xb9eb05 (0x7eb6004 0x0 0x0 0x0)
0x4469bf68 : 0xb5362c (0x7eb6004 0x1 0x7c637f0 0x7c63be8)
0x4469bf98 : 0x23e4ae (0x8af4400 0x7eb6004 0xfa6d03 0x7eb4028)
0x4469bfc8 : 0x2c7d0c (0x84ad60 0x0 0x10 0x92f8410)
Kernel Extensions in backtrace:
com.apple.NVDAResman.G7xxx(7.0.4)[6581C9F3-3221-4530-BEB4-627CB8D602AE]@0xb4c00 0->0xe41fff
dependency: com.apple.iokit.IOPCIFamily(2.7)[8087C029-833E-4B62-A8C3-2B074B4C55F7]@0xade000
dependency: com.apple.iokit.IONDRVSupport(2.3.4)[393829BA-614C-4ED7-B4AD-CE577A41C683]@0xb3 b000
dependency: com.apple.iokit.IOGraphicsFamily(2.3.4)[EE3F8FBE-3457-4F0E-A3A3-B9B1A44DCF6B]@0 xb07000
com.apple.nvidia.nv40hal.G7xxx(7.0.4)[C61073DF-524F-472B-A19F-3B80B884F6C5]@0x1 4b2000->0x15bdfff
dependency: com.apple.NVDAResman.G7xxx(7.0.4)[6581C9F3-3221-4530-BEB4-627CB8D602AE]@0xb4c00 0
BSD process name corresponding to current thread: kernel_task
Mac OS version:
11G63
Kernel version:
Darwin Kernel Version 11.4.2: Thu Aug 23 16:26:45 PDT 2012; root:xnu-1699.32.7~1/RELEASE_I386
Kernel UUID: 859B45FB-14BB-35ED-B823-08393C63E13B
System model name: MacPro1,1 (Mac-F4208DC8)
System uptime in nanoseconds: 37415286581
last loaded kext at 10244857365: com.apple.driver.AppleHWSensor 1.9.5d0 (addr 0x3125000, size 28672)
loaded kexts:
com.microsoft.driver.MicrosoftMouseUSB 8.2
com.microsoft.driver.MicrosoftMouse 8.2
com.microsoft.driver.MicrosoftKeyboardUSB 6.2.2
com.microsoft.driver.MicrosoftKeyboard 6.2.2
com.apple.driver.AppleHWSensor 1.9.5d0
com.apple.filesystems.autofs 3.0
com.apple.driver.AppleHDAHardwareConfigDriver 2.2.5a5
com.apple.driver.AudioAUUC 1.59
com.apple.driver.AppleHDA 2.2.5a5
com.apple.driver.AppleTyMCEDriver 1.0.2d2
com.apple.driver.AppleUpstreamUserClient 3.5.9
com.apple.driver.AppleMCCSControl 1.0.33
com.apple.kext.ATIFramebuffer 7.3.2
com.apple.iokit.IOUserEthernet 1.0.0d1
com.apple.GeForce 7.3.2
com.apple.iokit.IOBluetoothSerialManager 4.0.8f17
com.apple.GeForce7xxx 7.0.4
com.apple.Dont_Steal_Mac_OS_X 7.0.0
com.apple.driver.AudioIPCDriver 1.2.3
com.apple.driver.AppleMCEDriver 1.1.9
com.apple.ATIRadeonX3000 7.3.2
com.apple.driver.ACPI_SMC_PlatformPlugin 5.0.0d8
com.apple.driver.ApplePolicyControl 3.1.33
com.apple.driver.AppleLPC 1.6.0
com.apple.driver.CSRUSBBluetoothHCIController 4.0.8f17
com.apple.driver.CSRHIDTransitionDriver 4.0.8f17
com.apple.iokit.SCSITaskUserClient 3.2.1
com.apple.driver.XsanFilter 404
com.apple.AppleFSCompression.AppleFSCompressionTypeDataless 1.0.0d1
com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0d1
com.apple.BootCache 33
com.apple.iokit.IOAHCIBlockStorage 2.1.0
com.apple.driver.AppleFWOHCI 4.9.0
com.apple.driver.AirPortBrcm43224 501.36.15
com.apple.driver.AppleIntelPIIXATA 2.5.1
com.apple.driver.AppleAHCIPort 2.3.1
com.apple.driver.AppleUSBHub 5.1.0
com.apple.driver.AppleIntel8254XEthernet 2.1.3b1
com.apple.driver.AppleEFINVRAM 1.6.1
com.apple.driver.AppleUSBEHCI 5.1.0
com.apple.driver.AppleUSBUHCI 5.1.0
com.apple.driver.AppleACPIButtons 1.5
com.apple.driver.AppleRTC 1.5
com.apple.driver.AppleHPET 1.7
com.apple.driver.AppleSMBIOS 1.9
com.apple.driver.AppleACPIEC 1.5
com.apple.driver.AppleAPIC 1.6
com.apple.driver.AppleIntelCPUPowerManagementClient 195.0.0
com.apple.nke.applicationfirewall 3.2.30
com.apple.security.quarantine 1.4
com.apple.security.TMSafetyNet 8
com.apple.driver.AppleIntelCPUPowerManagement 195.0.0
com.apple.kext.triggers 1.0
com.apple.driver.DspFuncLib 2.2.5a5
com.apple.driver.AppleSMBusController 1.0.10d0
com.apple.iokit.IOSurface 80.0.2
com.apple.iokit.IOSerialFamily 10.0.5
com.apple.iokit.IOFireWireIP 2.2.5
com.apple.iokit.IOAudioFamily 1.8.6fc18
com.apple.kext.OSvKernDSPLib 1.3
com.apple.driver.AppleSMC 3.1.3d10
com.apple.driver.IOPlatformPluginLegacy 5.0.0d8
com.apple.nvidia.nv50hal 7.3.2
com.apple.driver.AppleGraphicsControl 3.1.33
com.apple.driver.AppleHDAController 2.2.5a5
com.apple.iokit.IOHDAFamily 2.2.5a5
com.apple.driver.AppleSMBusPCI 1.0.10d0
com.apple.nvidia.nvGK100hal 7.3.2
com.apple.driver.IOPlatformPluginFamily 5.1.1d6
com.apple.kext.ATI5000Controller 7.3.2
com.apple.kext.ATISupport 7.3.2
com.apple.nvidia.nvGF100hal 7.3.2
com.apple.NVDAResman 7.3.2
com.apple.nvidia.nv40hal.G7xxx 7.0.4
com.apple.NVDAResman.G7xxx 7.0.4
com.apple.iokit.IONDRVSupport 2.3.4
com.apple.iokit.IOGraphicsFamily 2.3.4
com.apple.driver.AppleUSBBluetoothHCIController 4.0.8f17
com.apple.iokit.IOBluetoothFamily 4.0.8f17
com.apple.driver.AppleFileSystemDriver 13
com.apple.iokit.IOUSBHIDDriver 5.0.0
com.apple.driver.AppleUSBComposite 5.0.0
com.apple.iokit.IOSCSIMultimediaCommandsDevice 3.2.1
com.apple.iokit.IOBDStorageFamily 1.7
com.apple.iokit.IODVDStorageFamily 1.7.1
com.apple.iokit.IOCDStorageFamily 1.7.1
com.apple.iokit.IOATAPIProtocolTransport 3.0.0
com.apple.iokit.IOSCSIArchitectureModelFamily 3.2.1
com.apple.iokit.IOFireWireFamily 4.4.8
com.apple.iokit.IO80211Family 420.3
com.apple.iokit.IOATAFamily 2.5.1
com.apple.iokit.IOAHCIFamily 2.0.8
com.apple.iokit.IONetworkingFamily 2.1
com.apple.iokit.IOUSBUserClient 5.0.0
com.apple.iokit.IOUSBFamily 5.1.0
com.apple.driver.AppleEFIRuntime 1.6.1
com.apple.iokit.IOHIDFamily 1.7.1
com.apple.iokit.IOSMBusFamily 1.1
com.apple.security.sandbox 177.8
com.apple.kext.AppleMatch 1.0.0d1
com.apple.driver.DiskImages 331.7
com.apple.iokit.IOStorageFamily 1.7.2
com.apple.driver.AppleKeyStore 28.18
com.apple.driver.AppleACPIPlatform 1.5
com.apple.iokit.IOPCIFamily 2.7
com.apple.iokit.IOACPIFamily 1.4