JDog2pt0

I'm sitting here minding my own business browsing the web and listening to music when suddenly the music starts skipping. The computer becomes totaly unresponsive then the theme switches from WinXP to Windows Classic, but it was tan instead of the blue and grey. Almost as soon as that happens the computer flat out crashes, reboots and theres a loud buzzing coming out of the speakers,(computer is only at POST) they are usb speakers. Now the computer has only started having it little quirks here and there since it was overclocked (only to 2.7Ghz) a few months ago and with dual 8800's running it, things tend to get toasty. Only reason I bring this up is because it has never done anything else close to that before, I have underclocked it to the original 2.4ghz. Just wondering if you guys know whats going on