Windows error messages... please help...

I recently installed a copy of Windows XP Pro. I reformatted my hard drive, installed windows, installed, my drivers, and it was ready. I was getting all sorts of error messages, and narrowed them down to being related to my chipset drivers. I uninstalled all nVidia stuff, and reinstalled the oldest drivers I had for it. My computer is more stable, but when I go play games; it usually will hang and give me the error message "stop 0x0000008E". It also has something about kmixer.sys, or win32k.sys or something. I get this error all the time and it's really annoying. I get another error that says " stop 0x00000050" when i try to do a virus scan with norton antivirus 2006 also. I would greatly appreciate any input that I can get on this frustrating issue.
Thanks.

(PC SPECS)........ upgrading soon

Athlon XP 2000+
512 MB DDR PC2100
300 GB Seagate Barricuda [boot]
40 GB Seagate Barricuda
Albatron KX18D Pro motherboard
nForce 2 Ultra 400
RADEON 9800 PRO

 

Defective memory (including main memory, L2 RAM cache, video RAM) or incompatible software (including remote control and antivirus software).

Bad Ram or Video card. Would be my guess.

 

I flashed my video card. It was originally a Sapphire 9800 PRO, I flashed it to an ATI 9800 PRO. It's worked fine for a long time though. Do you think that it might have made it unstable?

 

The card could be the cause of teh problem.

I would test the system ram with a porgram like Memtest86+.

Create a bootable CD from the image file, and boot your system with the CD.

If after 5 passes, no errors are found your RAM is good.