Can Anyone Help w/AV problem??

This has been going on too long.

Randomly, when playing a video or audio file the audio stops and the
video plays stop/start. To get it back, I need to reboot the system.

This is an ABIT MB w/KT133A chip (KT&A-RAID MB).
I thought I had this fixed for a while per the BIOS upgrades etc.
Something changed - It's back!!!

Tried:
playing with different programs;
setting BIOS to daults;
removing RAM;
rearranging RAM;
removing each bd other than video - visually I can tell if the problem
still exists;
eliminated RAID and ran from IDE connected drive;
replaced "puffy" capacitors.

I am running:
ABIT KT7A-RAID latest BIOS
HPT 2.32 driver
Athlon Tbred 2100+ @ 2266 mhz
133Mhz bus
core 1.825v BIOS - 1.87v real
nVidia GeForce 3 T200 latest driver
RAM = 1x256M Crucial PC133, 2x128M Hyundai PC133
MBM temps = case = 29°C core=44°C or about 15°C above ambient
Case open
XP

WHAT ELSE CAN I TRY????????????

thanks

cher