Screeching speakers!

[cavemangrinder]

Ive been having a problem with my computer speakers as of late. Sometimes when I turn on my computer and turn on the speakers, I get a screeching sound that pierces your ears. After a simple reboot, the speakers work normally again. Anyone have any idea what the hell is up with them? I am using the same drivers for my sound card that has been working for the past year without any problems.