R51 freezes when idle

[Randlaeufer]

I have a problem with my R51 1830 (Centrino):

Whenever I leave the Thinkpad running idle for about 10 minutes (I don't touch mouse or keyboard) Windows freezes and the plastic above the fan on the left feels warmer than it probably should. The Thinkpad doesn't ever freeze if I put it on top of two books. Also I can work and play 3D games all day long without a freeze.

All updates suggested by the Software Installer have been installed. Also the freeze happens regardless of whether I have open applications or not.

Any ideas concerning the cause of this issue will be greatly appreciated.

[RS_003]

Dust in the fan?

[IBM Thinkpad]

Hard Disk problem???