Log-off/Switch User Errors

[Kaos Kid]

Ever since Thanksgiving when we had some power surges I have been getting errors after I have used the "switch users" function. This box is using WinXP Pro x86 SP3. It has 2x2GB of Corsair XMS PC3-12800 (DDR3-1600) CL8 (these errors show up whether I let the mobo pick stock configs 1333 @ 9-9-9-24, or I "correct" the settings to 1600 @ 8-8-8-24 with volt adjustment to 1.65v which is what the memory is supposed to be anyway) I leave this box on 24/7 for the most part, so I use the "switch user" function so my torrents can still run in the background but my wife can log into her account and check email. After a lengthy period of sitting, sometimes it asks for my administrator password (old school "computer locked" login screen) and I get the following error involving memory:

The instruction of 0x00000000 referenced memory at 0x00000000. The memory could not be "read". Click OK to terminate the program.

The numbers vary depending on which program is involved in the errors. When I do log in to my own account, Everest has usually terminated, and sometimes other programs as well, or at least the icons disappear from my systray. Icons on the desktop sometimes disappear as well. I even get visual errors when my screen comes back up and my firefox page happens to be onscreen, such as some emails have blank lines. Clicking on them lets me read the emails, and sometimes the words/icons reappear after clicking on the space where they should be.

ALSO I get similar problems after I run a full extensive scan with COMODO, M$ Security Essentials, and Malwarebytes Pro, so I wonder if I have a hidden virus that is fubar'ing things when something loads it up in a scan. Nothing shows out of the ordinary in the scans up until the errors suddenly appear.

I ran memtest 86+ through a bootable cd and let it go one full pass (about 15 minutes) without any errors at all, though I realize I should probably let it go longer I didn't want to leave it running all nite so I will do it again today during such time as I can monitor it for an extended period.

After rebooting things seem fine.


My question is, considering the power surge SEEMS to be the beginning of this, which of the following scenarios seem most likely?

1) Power surge damaged motherboard memory controllers

2) Power surge damaged the memory itself and it only manifests after certain areas are accessed

3) Power surge corrupted some file(s) in the OS or Registry that only manifests after an extended period.

4) Power surge damaged the CPU (Phenom2 X2 550 that I got from Skier) and only manifests after a period of time. Errors happen whether I am at stock x2 or using ACC to unlock it to 3 cores as a B55 X4)

5) None of these, and something else you may be able to suggest?

Any help/insight is greatly appreciated!

[Major_A]

Could be any of those. Have you run Memtest overnight? Have you ran a file check of the Windows installation?
Memtest86+
http://majorgeeks.com/Memtest86_d4226.html
or
Windows Online Crash Analysis - Memory Diagnostic
http://oca.microsoft.com/en/windiag.asp

Running a check of the XP file system.
Open up a command prompt and type sfc /scannow and let it do it's checks. In the event it doesn't find anything try running chkdsk :c /f in the command prompt. Your Windows drive might not be :C so change that to the appropriate drive if you need to.

[Kaos Kid]

No memtest overnite yet, but plan on it. Actually I just remembered that I have 2x2 GSkill memory in my box downstairs so I swapped them into this box and will see if the errors recreate with known good memory (the box downstairs wasn't running during the surge, and its psu switch was off as well so hopefully nothing ever made it to the mobo/memory in that box. If the errors don't continue I will run memtest overnite on the Corsair just to confirm. Thanks for the links, they will be used as time permits.