need help asap >.<

ok here the problem...i was watching a movie on my pc like i do most of the time but then my moniter say no sign, going to sleep mode(i did try to unpulg and shutoff everything and start again, i did try to move the mouse and bang some keyboard still nothing, like ctrl+alt+del)...than i restart the pc and watch the movie again but like 10-15min after ..again go to the sleep mode! so here are the thing i try before post here and still got this problem...(not sure if im watching THAT very movie make the pc go poo) system restore, run spybot search and destory, ad-ware SE, CCleaner, Regscrub XP...thats about it...right now ill wait to see if its that movie caseing the problem...btw movie is dvdrip.xvid.

 

ok i think its the movie cuz its been a hour or so and the pc still working fine...i did use avast scan the movie but noting come up...if anyone know how to fix this problem plesae help~