Did you find a solution to this by any chance? I have the same problem and my laptop is also from one of the older (discontinued) models (A300 1EI)...what worries me is that it also happens when I boot into ubuntu so seems like a hardware issue...the comp definitely overheats (SpeedFan tells me it gets up to 68C, though usually at 50)...the last BIOS update was 2.2 (which is a few years old I think).
Thanks and regards,
My Toshiba Satellite A300 1J1 keeps restarting itself. This seems to happen at random, sometimes it has only just reached the home screen when it turns off other times it can be on for a few hours.
I have searched the web and people suggested it may be overheating so I took the laptop apart and cleaned the fan but this has not helped at all.
I have now found that if I start the laptop in safemode with networking the laptop does not restart at all.
Does anyone have any ideas how to fix this problem?