Yeah, sounds like you've got some kind of funky temp-reading/eval thing going on.
I get the same problems with my MSI board and it's stupid CoreCell software. It tells me that, idle, my CPU is running at 90C! LOL And it's even underclocked at that state. it's a AMD XP 3200 processor, which the damn CoreCell loads at 158x11 (which gives a reading of 90C), which I have set to automatically bump up to its normal opperating speed of 200x11 (which makes CoreCenter flip out like my computer is going to vaporize itself in a burning ball of flames...which it doesn't...of course...)
Still haven't figured that bugger out. POS MSI software.
Anyway, I suggest you either figure out what the error offset is, or go through the list of temp-monitoring components on your box and see what's messed up. Could be software, hardware heat sensor, who knows.