I can't reboot or shutdown

[Soren Hauberg]

Hi
Yesterday I installed Ubuntu on my old'n'crappy laptop (it's a IBM 
thinkpad 240, 300Mhz Celeron). Allmost everything works, except I can't 
shutdown or reboot. If I try to shutdown everything works except the 
machine doesn't power off and I have to do that manualy (I hate holding 
the power button for three seconds) and if I reboot the machine hangs 
once it get to the actual rebooting.

/Soren