This is quite common as the heatsink is clogged (how long since being cleaned?), lifted off (it's 3 years old!) or the battery has failed and causing the charging circuits to go bananas.
Are you seeing the forum note? Here it is -> Note: If you're asking for technical help, please be sure to include all your system info, including operating system, model number, and any other specifics related to the problem.
Why I ask is you didn't tell the last bit of detail needed for me to not write about those bad old Pentium 4 laptops.
Also tell me about your cleaning cycle. Yearly, never?
My 3 year-old Toshiba Satellite, running XP Home, has suddenly started to switch itself over to battery power even though I am still connected to the AC. I've found that I can get it back over to AC by unplugging and immediately replugging. BUT the fan is then running fulltime and eventually the computer shuts down. The error message on reboot seems to indicate a problem either with a driver or (more likely) with the power supply. Has anyone had a similar problem? If so, how did you solve it?
Thanks a million. Mike