If your computer starts randomly playing “Fur Elise” or “It’s a Small World”, don’t worry. It’s not a virus.
It’s just an indication sent to the PC speaker from the computer’s BIOS that the CPU fan is failing or has failed., or that the power supply voltages have drifed out of tolerance.

Think I’m fucking kidding?

Thenk look at this Microsoft Knowledge Base article.

Now, this only applies to
• Microsoft Windows 2000 Server
• Microsoft Windows 2000 Professional Edition
• Microsoft Windows 95
• Microsoft Windows 98 Standard Edition
• Microsoft Windows 98 Second Edition
• Microsoft Windows NT Server 4.0 Standard Edition

So if you’re running XP or Vista, then you’re shit out of luck. You won’t have any way of knowing if your fan is failing.