Fan/heat management issues on TP41p

[Jesse Sheidlower]

I have an IBM ThinkPad T41p running FreeBSD 5.3-STABLE. I haven't
touched anything system-related in a while.

Two days ago I realized that my fan was on even though the system
was under a very light load. After some time of this, I shut the
lid to suspend it, and the fan was off on resume. That night
the machine crashed, and /var/log/messages showed that it had shut
itself down because it got too hot. I left it up anyway, and the
same thing happened last night. Today, however, the fan suddenly
turned itself back on, and now it's running constantly under no
load.

Is this likely to be a hardware problem, and I should just bring 
it in for service? Or are there software issues I should explore
first? I don't have another OS loaded to see if things are
different. I'm running ACPI, but have no idea what this means as
far as heat management is concerned.

Thanks.

Jesse Sheidlower