hey dude wassup. im kinda having the same problem except not really. my comp is a month old, in built it myself and made it for pc gaming:

core 2 duo e8400 at 3.0 ghz
9800gt nvidea (used to be a radeon 4850 but got too hot and froze 2 much)
2gb RAM (had 4gb but took 2 out cus i got blue screen two much)
pretty much other good gaming stuff

and it worked the first few days but then after a long day of running i made it play grid and it froze with a crackling sound coming from the speakers. i was like o crap so i shut it down. from then on it loaded up slower, it randomly froze, and i got canstant blue screens (this is when i had 4 gb ram and radeon 4850).
i thought tht my graphics card broke so i took it back to the store and got the 9800gt and it eliminated the freezing, but i still got blue screens occasionally (like every 1 in 5 times running my comp) so i took out 2gb of ram and i dont get blue screens any more. i thought my problems were fixed, but now whenever i play crysis my comp freezes, the mouse and keyboard shut off as if there not plugged in, and i get this hideous crackling sound from my speakers. i turned it off and reloaded crysis but now my pointer activates the buttons in the game like 3 inches down and to the right. HELP!!!