There are several issues with overheating in 11.10. At least most of those are fixed in Precise (which will become 12.04). I had similar issues with all my computers on 11.10, but never since. (Never before 11.10 either).

If you really want to get into it, you can try upgrading your kernel. Or maybe you'll rather want to upgrade to 12.04 Beta 1 on the first of March. Of course, you could always download it now and try it in a memory stick or something, just to confirm that all the issues have been resolved. They should.