Noisy cooling fan

[Dan Davison <davison@uchicago.edu>]

I have a year-old laptop with a pentium 4, running Debian testing with
kernel 2.6.6. After an initial 5 minutes of calm after booting, the
cooling fan comes on and remains on in a state of relatively high
activity; it is very noisy). 

Oddly, for the last two weeks, it worked every day in quiet or inactive
fan states, unless given something very processor-intensive to do. I was
using the /proc/acpi/processor interface to throttle down the processor
when I didn't need high speed and this certainly has the effect of
reducing performance. It was my impression that it also helped reduce the
fan activity during the two-week "quiet spell". However it's now back to
its vacuum-cleaner sort of level of noise (after the initial 5 minutes
after boot), and throttling the processor right down to minimum seems to
have no effect on the fan activity, although it still controls
performance.

I would like to know whether this is a hardware or software issue, and if
the latter whether it perhaps indicates that I am not taking proper
advantage of some acpi-related features available in 2.6 kernels. Does any
one have an opinion, or could you give me some pointers as to how to
proceed?

Thanks a lot,

Dan

p.s. The laptop brand is "HugeBee".