BSOD - Page fault in non paged area

Lately I've been having some trouble with computer. I'm getting two BSOD's.
1. Stop 0x00000001 APC index mismatch. This one has heapend two or three times so far and only when booting my computer when my system is loading windows.
2. Stop 0x00000050 Page fault in non pages area. This one heapened this morning when I turned on my computer, allso while loading windows.

Noteable things(that I remeber) I did recently:
- A month or two back I did a clean install of my videocard drivers. (uninstall -> driversweeper -> install).
- Update to the new catalyst (APC index mismatch did allready heapen before that)
- Uninstall pctools firewall -> install comodo firewall.
- Defrag my harddrive with Obit Smart defrag 2

I'm runnings Windows Vista 64x on a 2~3 y old system. I Reinstalled windows once, I think it was roughly a year ago.

I did some research and, as with most BSOD's it said it is either a driver issue or hardware malfunction. Since I dont really that much about the subject and have no clue on how to fix it, I defer to people with more knowledge on the subject.

Hoping its not a harware issue,

Ben

Welcome
You have given us only one dump, which is not usually enough to diagnose a BSOD. In your case, however, the cause was a common problem, your anti Virus.
Uninstall Avast. In lieu of Avast use Microsoft Security Essentials and for extra protection Malwarebytes. After the new AV if you still experience BSOD, post.
Be sure to go to the Avast website and use their uninstaller to be sure that all remnanats of Avast are removed.

Thanks, I'll be sure to do that.

After the new Anti Virus, be sure to post back if you have any additional BSODS