Help!  Close to start up my laptop keeps hibernating over and over,  After about 10 times it's OK for th erest of the day.

Heard of this before?

(when I say hibernting what I mean is the screen goes blank and I have to press the power switch to restart.  Pressing the button takes me straing to the log-in screen (i.e no boot) and then to where I left off.  Not sure if this is hibernate or sleep or what.

Please help, this is VERY annoying.

Thanks