Cant boot after one hour or sleep or shut down, getting black screen and the standby light is on.

Hi everybody,

I have the strangest problem on macbook 2.1 mid 2007.

When I shut it down for an hour or more it it wont boot normally, it shows a grey screen for a few seconds and then the screen turns black and the standby led turns on and the only way to start it is to take out the battary and power or sometimes to do a hard shut down.

when i set it to sleep for more than an hour the same thing happens but in sleep it seems to take more than one hour.

I had some help from one mac expert who didn't manage to fix the problem.

anyone has an idea what is it?

Thanks =)