Computer freezes and ringing noise comes from speakers

[rickfin]

Hi! Once again I get these strange problems. My computer freezes and a ringing sound comes from the speakers and I have press reset button. After restart no message from windows or anything like that. My e6600 is overclocked but that shouldn't be the problem. I haven't have these issues before. The comp is orthos blend and small ffts stable 12 hours and I have ran memtest86 12 hours without errors. Could my soundcard be the problem?The rig:
e6600 @8x400 1.25v
gigabyte ds3 f8i bios
geild pc6400 2 gt
creative x-fi xtreme music
Siverstone Zeus ST56ZF