9.10 problem

[Gordon]

I have a problem with 9.10 on my Toshiba L40 Satellite 2GB RAM, dual 
core T2330 1.6GHz processors which I don't /think/ happened with 9.04.
Every so often, randomly, there's a loud "click" and the machine 
instantly switches off. Happens with the kernel that ships with 9.10, 
and the updated kernel.
The same doesn't happen with Windows 7 on the same machine - dual boot.
Anyone had this?
Any fix for it?