I have an Acer Aspire One D250-1197. I really better type fast before it overheats again...

For some reason, I'm having a problem with heat on my netbook only when I run Joli OS (Ubuntu 9.10 LTS?). When I leave it idle, with nothing running (other than the regular Joli OS desktop and a couple of doing-nothing terminals), heat slowly builds up to the point where the netbook is burning hot to the touch. I have never had this problem when running Windows 7 Starter (even though it gives me plenty of other headaches). It seems that the fan is spinning, but not fast enough to keep up with the heat buildup.

Is there something wrong with the fan drivers? The computer doesn't seem to recognize that it is overheating. What can I do to solve this problem (other than shut it off or use Windows)? I'm currently on the wrong side of Earth (I mean, on vacation), so I just need a temporary fix, such as a driver I can install. Also, I have to use Linux, because I have to share out the wired connection in hotels wirelessly to the iPhones.

EDIT: I'm switching from Joli OS to a more "proper" and up to date distribution (Xubuntu 13.04). I'll see if it still has the heat problem and try @nod's cpufreq idea.