Vista Sleep/Hibernate crash

Hello,
I have a problem with my Toshiba Satellite laptop running Windows Vista
Ultimate.

Until recently, everything was working fine, but now whenever I try to
put the laptop into Sleep or Hibernate, the screen fades to black, as if
it is going to sleep, but the blue power light stays on, rather than the
pulsating orange that is supposed to happen. Then after a couple of
seconds, the computer just stops and powers off. When I reboot, Windows
tells me it wasn't shut down correctly etc.

I'm all up-to-date on Windows Updates, and windows can't find a
solution when I report the problem.

The other day I found it started to restart when I clicked Shut down,
but this only occurred when the laptop was plugged in to the mains power
supply.]

I'd really apreciate any help at all on this.

Thanks
helloworld


--
helloworld