weird failure on boot + squeaking noise

I'm new here, so I hope I'm in the right forum and that I'm not asking an obvious question...I couldn't find what I was looking for in the search function. Thanks.

I've had my Acer Aspire One (AOA 150, if that means anything, and with XP) for about 7 months. I've used it a LOT with pretty much no problems at all. Today I turned it on and worked on it for about 5-10 minutes, I was just using Opera, nothing out of the ordinary, when all of a sudden it made a squeaking noise and turned black. I tried to boot it back up, it went to the Windows loading screen with the progress bar, and after a few seconds it made the same squeak and shut down again.

When I booted again it gave me the options of safe mode and last successful settings. I tried both and I got the same problem with the shutdown and the same squeak noise. Then I panicked for a while about my lost files, and about 10 minutes later I went back and tried it again. This time I didn't have it plugged into the power source (if that's significant?) and it booted it up 100% fine, no squeaking. I backed up all my files and stuff, and I've tried restarting it several times to see if I'd get the same problem. Nope - it works totally fine now.

I'm wondering what would have caused this problem - doesn't the squeak sound like a hardware issue? Or could it maybe be a virus? - and what I should do about it. It's still under warrantee so I could always send it in but if this was just a freak accident - power surge, maybe? - I don't want to bother about it. Any advice or experiences? Thanks in advice.

Edit: I forgot to mention that I think I've ruled out overheating, since it was definitely not hot. I've had it get quite hot before in the past, too, with no problems.