5100 working surface (keyboard, touchpad, wrist rest) hotter than necessary

Have had my 5100 for a year now. After it has been on for a little while it becomes hard to use the keyboard because the surface gets really hot. I hear the fan running longer than usual. The fan vents have plenty of room to get air circulation, as the notebook sits flat on a desk. A visual inspection of the vents shows that they are clear.

I shut the 5100 down when I'm not using it for extended periods of time and every night.

I use my 5100 for work and school, so this is getting to be a drag. Glad I popped for the extended warranty!

Beyond getting an external USB keyboard (which I now wish I had) and shutting the thing down for 30 minutes every other hour, what's the solution?

Thanks!

Inspiron 5100
512mb RAM
32mb Video
30gb HDD
XGA