Spontaneous Restarts

[Belia]

My MacBook has a problem: it spontaneous restarts whenever you dont' expect it. Since I give webtrainings and use this machine for demo's I have a serious problem here. Apple found no hardware problems. Last week I formatted the machine, I was confinced the problem should be over.

You guessed... it isn't over. Yesterday the problem came up again.

Why this issue on this forum? Because this morning I made a stupid mistake in backing up according to a new genius system I had figured out. Not as genius as I thought: it deleted the complete system on my main machine (which is not my MacBook), only some userfiles where leftover.

Thanx to SD all I had to do was put back the deleted system from my clone and I was fit and running again. This clone was freshly made from the same main machine. I only had worked a few hours on about 10 files on the clone on my MacBook (startup disk from MacBook, I didn't start up from the clone).

And now come the clue: since I put back the system from the clone my main machine had the same problem as my MacBook, it restarts as it likes!!!!! How is this possible??? The clone I put back is an exact copy from the original system on the main machine. Only about 10 files are changed. What else has there been going on between MacBook and Clone and main Machine?