Comment 5 for bug 93243

temporary fix:
after some online reading, I tried the solution described here:

http://www.vmware.com/community/message.jspa?messageID=332390

In my case, the BIOS of my machine controls the fan, and upon boot up, when ACPI kicks in, the fan shuts off.

I edited /boot/grub/menu.lst and found the line for my kernel
and added

acpi=off noacpi

to the end of that.

so mine looks like:

title Ubuntu, kernel 2.6.17-11-386
root (hd0,1)
kernel /boot/vmlinuz-2.6.17-11-386 root=UUID=0a5a4656-cf6d-4dc0-acd9-25908ebd2177 ro splash acpi=off noacpi
initrd /boot/initrd.img-2.6.17-11-386
savedefault
boot

(end grub menu)
it goes without saying this isn't the definitive cure for this problem, but my fan is running.