Windows 7: BSOD when coming back from sleep.

This all started a week or so ago: whenever I bring my computer back from sleep mode, I get a black screen for about 30 seconds and then a BSOD. The dump data says it's likely caused by csrss.exe.

I've done some searching and found some possible solutions. Thus far, I've tried the following without anything working:

I've wiped my hard drive and reinstalled Windows 7.
I've updated my video card drivers.
I've uninstalled my video card drivers and video card, then restarted my computer and let Windows reinstall them.
I've updated my BIOS.
I read something about setting suspend mode to S3, but my BIOS doesn't give that option.
I've run CHKDSK (no bad sectors were found).
I've run a full system scan and a boot-time scan thru Avast (nothing was found).
I've cleaned out all the dust from the computer's case.

Is there anything I can do to prevent this besides disabling the sleep function?

My system: Windows 7 Home Premium x64 (upgraded from Vista x64)
It's an HP Pavilion e9120y I got refurbished from Fry's two years ago. I haven't had any problems with it until now.


I've attached the dump files here. Thanks for your help.