I've got a Toshiba A200 laptop Model PSAF6A-0W00IN.
Symptoms are that it keeps rebooting at random times from a cold start to anytime after windows vista logon. Sometimes fails to even get to windows logon. Case and air vent gets hot. The machine definitely runs better using only the battery power both on highest or lowest power settings and battery seems to hold a charge okay. BUT crashes still occur either using AC or batter power. I've pulled the machine apart and cleaned the fan. Seems to be working okay. Maybe running too slowly? Could it be a AC/DC power inverter? If so, how can I check it? Changed start up to Diagnosis only using MSCONFIG, but no difference. Can anyone provide any ideas please?
It could be heat, power or a RAM fault. Have you been running a temp monitoring program?
The heatsink on the CPU could be the problem. If the heatsink/thermal compound is the reason it could let the CPU overheat and shut down even with a clean fan.
Have you run the laptop in much cooler environment? (like outside on a cool night?)