PC Randomly Turnoffs

[scarfase99]

Ok guys, here's my dilemma, Win2000/ME dual-boot Athlon 650, 512mb, 60gb, Matrox G450 AGP, WinTV Theater, and every now and then, when i have my computer on, it's as if the monitors just turn off. But it happens sporadically, and for example, if WinTV is on, the volume for the show stays, the computer makes the same noise with fans, and the only way i can fix it is by turning the power on and off. Can anyone help me out with this? It's really annoying. Oh yeh, btw, it's in a new Skyhawk Aluminum case, i never had this problem in my last generic case which had the same stuff.