Laptop freezing (but only in some places)

I have a laptop that recently began to freeze randomly. It often freezes (as in cursor doesn't move, and caps/number locks keys don't work, and I have to turn it off manually by holding on the power button) as the laptop boots up on the blue "Welcome" screen for Windows XP. And sometimes it boots up completely and works perfectly fine for a few minutes until it freezes up again.

But the part I find really weird was that when I bring the computer to the school library, it works perfectly fine. And as soon as I turn in on back in my room, it continues to have the same problem.

This happened not just once, but for four days in a row now. It would freeze up when I turn it on in my room, but would work perfectly fine when I use it at the school library or the computer lab. I tried to use the computer in almost the same exactly condition (on a flat surface and without power plugged in), and the temperature does seem like it could be a factor.

I thought I was going crazy, so I decided to post the problem on here and see if people who actually know a little something about computers might know what's going on. Thanks!