Kernel panic during sleep mode

Question

Could someone possibly shed some light on a 0x400 trap. I got the following yesterday afternoon:
"Unresolved kernel trap(cpu 0): 0x400 - Inst access DAR=0x000000003BF2D160 PC=0x0000000000000000
Latest crash info for cpu 0:
Exception state (sv=0x49A57780)
PC=0x00000000; MSR=0x40009030; DAR=0x3BF2D160; DSISR=0x40000000; LR=0x002C8250; R1=0x21D93D20; XCP=0x00000010 (0x400 - Inst access)
Backtrace:
0x002C81EC 0x002C5874 0x005396EC 0x0003C744 0x000A9894
Kernel loadable modules in backtrace (with dependencies):
com.apple.iokit.IOSCSIArchitectureModelFamily(1.4.4)@0x52c000
Proceeding back via exception chain:
Exception state (sv=0x49A57780)
previously dumped as "Latest" state. skipping...
Exception state (sv=0x3BC28780)
PC=0x00000000; MSR=0x0000D030; DAR=0x00000000; DSISR=0x00000000; LR=0x00000000; R1=0x00000000; XCP=0x00000000 (Unknown)"
Trying to decipher the system log seems to indicate a problem with my USB hub, the iMac doesn't seem to be able to communicate with it. This has happened before - usually there are no applications open and the computer is in sleep mode. The problem then occurs when I try to wake it; usually a light blinks on the Iogear hub for a short time and then goes out - when I get a panic, three lights stay on continuously, the fans are whirring and absolutely nothing happens, the screen remains black. There also is no pulsating light on the front bezel of the iMac. The only solution is a forced shutdown. Once I restarted, all seemed well again. BTW, this hub (hub/card reader combo) does not have any lights on when everything is working as it should.
I also just remembered that occasionally, my keyboard or mouse (both plugged into the hub) will become unresponsive; once I unplug them and plug back in, they're fine. I've already tried a different hub (Macally) and the very same thing happened. I don't know if these could be related?

Answer 1

Hi, Barbara.
The line
Unresolved kernel trap(cpu 0): 0x400 - Inst access
in your panic log indicates an 0x400 (Instruction Access) panic. An 0x400 (Instruction access) panic occurs when the processor cannot access the next instruction to be executed.
Potential causes include RAM problems, hard disk corruption, and programming errors. "Programming errors" in this case can include invalid instructions and violations of protected memory, however it is often difficult to differentiate a programming error from a RAM or hard disk problem since the latter two issues can cause a valid instruction to appear invalid. Likewise, this opens the door to the potential for processor errors, i.e. defective processor or other problems with the logic board.
Kernel loadable modules in the backtrace are flagging
com.apple.iokit.IOSCSIArchitectureModelFamily(1.4.4)@0x52c000
This indicates an issue with "...SCSI, USB (Storage), FireWire SBP-2 and ATAPI devices."as described here.
It could very likely be the USB hub/card-reader combo you cited, or it could be a deeper problem with your Mac. Does the problem occur when you have media in the card reader of the USB hub/card-reader combo?
See my "Resolving Kernel Panics" FAQ. This FAQ includes step-by-step instructions for identifying and resolving some of the most common causes of kernel panics.
My FAQ is a roadmap: start at the beginning and work through to the end, following the instruction in the order specified, including the "If all else fails..." section if a cause or resolution is not found in an earlier troubleshooting step therein.
Good luck!
Dr. Smoke
Author: Troubleshooting Mac® OS X
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