System lock up during video and/or audio playback

i apologize in advance but this is going to be vague. now i'm a pretty seasoned computer guy. built my own computer and it's been going great until recently. every now and then my system will completely lock up while i'm on the computer and i'm always playing either music or a video. no matter which player i use whether it be winamp, quicktime, or windows media player it locks up all the same. usually it locks up hard enough that i have to manually shut it down. very few times will it only lock up for a few seconds. and when it locks up, whatever was playing freezes the sound with it so this awful, repetitive sound is being held over my speakers when it locks up.

now my hdd setup is a little different now than it says in my profile. i have 3 seagate drives. all the same size at 300gb and model number st3300831as. 2 of these are in RAID0 and the other stands alone for my big stuff like the music and videos which all in all add up to about 250gb. and one other hdd that's a western digital 250gb and the model number for that is wd2500ys-o1shb1.

the reason i'm being so specific on the hdds is because i have reason to believe the problem may lie within them. but i could be wrong. please help because i've researched this and tried a dozen things but a system lock up is much to broad of a topic to be narrowed down through simple searching.