If my memory serves me correctly Hooky its an AMD Athlon 1.4
So I dont think its anything to worry unduly about.
Mine runs around 60/65 and my server pc has had a few warning beeps when re encoding a film at 100% cpu usage for a few hours, its set at 80 for warning and shut down at 90 or maybe 95 and its never shut down yet.
I dont think that the bios is all that accurate unless its one of the mobos with a connector for a temperature probe on it.
I think Serenitys problem is her PSU as it needs resetting after the pc has switched off, by unplugging it from the mains and then reconnecting before it will start up again