Memory issues/corruption on a GA-P35-DS3R under 32bit XP Pro SP2

I apologize upfront that this is a little bit long. Please stay with me.

Ok, weird problems going on as of late. Not sure of cause. It could be Mobo, RAM, CPU, Video, or OS. So, I'm going to start here since it is a Gigabyte board.

Here's the scenario.

Sept. 2007
Built new system with following specs:
Intel C2D E6750 | Gigabyte GA-P35-DS3R | eVGA 8800GTS (320) | Antec Solo Case | Corsair 520HX PSU | WD RE 160gb | WD RE 320gb | 2GB RAM | XP Pro SP2 - 32 bit

No overclock; iirc, most BIOS settings are default. Memory specifically is this one bought from NewEgg:
Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model BL2KIT12864AA804 - Retail

Been stable. No issues that I've noticed.


June 2008
Price dropped on same memory. Decided to order another set. Realized that XP would not see full amount but decided to go for it anyway. Order was for the same exact kit.
Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model BL2KIT12864AA804 - Retail

When I first put it in, the system seemed to have problems booting. I don't remember exactly now. I know I swapped slots, etc. but eventually with all 4 sticks in, system booted and seemed fine.


July 2008
May or may not be related but I started noticing some graphical issues during play of Civ4. Wasn't sure if it was video card or the mod packs I had loaded for Civ or a combination of. I uninstalled completely the video driver and updated to newest and removed the mod packs. Since then has been fine (when I've had time to play!)


THIS WEEKEND
Was doing some research on net. Using Firefox. Multiple tabs open. Started getting a pop up message from systray that file c:\windows\apppatch\acgenral.dll was corrupt and Firefox crashed a couple times. System otherwise OK. Went to bed for night. Next day, walked into a BSOD. Didn't write it down, but do remember it said "Memory Management." uh oh.

So, I rebooted and let it run chkdsk which it said it needed. It did list a couple of problem files including imm32.dll, mapping1.map, and compstui.dll. So now I'm starting to worry more about hard drive issues than memory. System finished chkdsk and booted into Windows. I checked into Event Viewer and did have quite a few entries about mapping1.map being unavailable as well as just one or two about imm32.dll. I think there were one or two other files mentioned too, but I don't remember which.

I launched Outlook to check my mail. It started but then gave a "Sorry there is an error and Outlook needs to close" message. The data referenced module: unknown and exception 0xc0000005. This happened a couple times and then I went back to Event Viewer. In addition to the 0xc0000005 exception, I also had an entry about MOF files for Office (no idea what those are).

I did a little searching and found some posts that the MOF error could be related to Profiles and that removing the existing and adding a new profile might help. So I copied my pst files to another location and went through Control Panel to the Mail utility to try to add a new profile only to get an error that it couldn't open mailprofcfg.cpl (may not be the exact right name).

At this point I tried to go through Control Panel > Add/Remove Programs and "Repair" Office 2003 only it didn't seem to try to do anything. I then decided to do an Uninstall/Reinstall of Office. Only I couldn't seem to get it to do anything. So then I ran the Ms Installer Cleanup Utility which wouldn't run but at least told me it needed imm32.dll (one of the corrupt files). I was able to restore that file and the Installer CleanUp Utility ran and then I was able to successfully run uninstall/reinstall for Office. And after that I was able to launch Outlook. Whew.

BUT

Just when I was relaxing, I launched another program on my system and got another 0xc0000005 exception error! (Application was freeware Snow Soft Merger. It merges txt and html files into single files).

So I gave in and downloaded MemTest86+ v2.01 and ran that last night. It ran for 5hrs 50 minutes with NO errors. It listed the memory at 5-5-5-18. I need to double check the BIOS settings for that. I then ran chkdsk with /R to look for bad sectors. It ran and reports 0kb in bad sectors.

I've done some research (while at work, shhh!) on 0xc0000005 and found http://www.updatexp.com/0xc0000005.html. Not sure I want to change the DEP setting, but I might do it. I am considering running WinDiag as a backup to Memtest just to confirm. I don't typically run antispyware stuff; my systems have been fine behind my routers for the last couple years, and I'm pretty conservative in what I run, but I'm going to download and run a few to see if they detect anything. I have been running Avast AntiVirus.

If problems persist, then I will take out the newest 2gb and return to just running my older 2gb alone.

Also, fwiw, my paging file is set to custom from 1.5 to 3gb. I should change that to windows managed?

What else should I look for or try? I can post more info on my BIOS settings and such when I get home tonight. Which malware detection programs are best?