Video causes random freeze ups

[sv]

When I play video on windows media player, DVD or any
complex animation from web pages or advertisements the
computer freezes. Sometimes a few seconds into the video
play, sometimes minutes...is completely random.
Tried reinstalling XP,checking drivers, changing the RAM,
installing additional fan...nothing seems to work.
Any ideas?
Please!?
Thanks

 

[nevo]

service pack and obviesly update media player.
nevo