http://support.microsoft.com/kb/261186
I don't know what I'd do if my computer started playing "It's a Small World" at random. Probably roll on the floor laughing...
That makes me want to find my old IBM and break it just to make that happen!
I've actually encountered this on a Gateway at a previous job. The problem occurred whenever anything was sent to the printer (weird, I know). After replacing the speakers, printer, and motherboard with no luck we sent the damn thing in (and it came back with a new PSU).
Also, at first I thought this topic would be about this (http://www.ibm.com/developerworks/linux/library/os-linuxmusic/index.html). Which is really, really cool in my opinion. I think I read an article on slashdot about a year back touting its success in a server room environment.
I linked that too a whole bunch of friends on my msn list a while ago, everyone seemed to enjoy it. :)