video files playing problem

[unvi$ible]

hi Nihil
Windows Xp Version 2002 Service pack 2, AMD Athlon5200+ 2 GIG Memory (800),
NVIDIA GFORCE 8500GT with updated driver 07/10/2008.gigabyte motherboard.
All movies are watched from hard disk.
Problem has started after 2-3 months-pc is 6 months old.
Dvd ad4 20a4p.Video files are ati files.He uses jet audio and windows player to play it too-same problem.
Codecs are ones which comes with jet audio xbvid mpeg-4.
i done virus scan, addaware scan, spybot scan, i updated video card driver it was one from 2007 -same problem.
i couldnt catch up error message but its something like this "i_rql_no less then_equal"

Ilooked into event viewer- service control manager 7034 and another one is system error 1003.They repeat few times, probably when system crashes.
Nothing in hardware has been changed and no drivers have been updated apart from video card i did today.
System is only 6 months old.
i will look into few things but i think of software conflict/problem.