I would think that your powersupply is on its last leg or an internal fan at the CPU is clogged up and needs cleaning or replacement. I don't know much about the internal workings of a laptop but those are two areas I would check quickly.
TONI
My satellite 1905 overheats when the processor utilization reaches 100% This occurs when doing Norton Virscan or intest file transfer. I am running windows xp, have 512 Men and a 2 Gig machine. The machine then reboots

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