We have an IBM T21 Thinkpad running Windows XP Professional which seems to
be overheating.

On startup, the CPU fan runs for a few seconds and then stops. This means
that the Thinkpad will run for about 15 - 20 minutes before the processor
overheats and shuts down, causing the Thinkpad to lock up.

The fan is o.k. because if you take it out and drive it from an external
power supply it will run quite happily.

In an attempt to cure this we have updated the Bios, installed the correct
configuration utility, installed the battery maximiser, the ACPI driver, the
updated power drivers for XP and the support files for XP. The fan still
doesn't run.

We are now out of ideas, apart from the fact that it may be a problem with
the system board. Before we go through the time and expense of installing a
new board we were wondering if there was anything else that we missed
because we can't see the wood for the trees at the moment