sswilson: it was the sensor...i think
I had the same problem, I think you have a problem with the senzor
I don't think your temp of the cpu is 13C or over 40...check it out in the bios...
Speedfan yesterday showed me Cpu temp:23C but that was impossible, now everything works..
Try to use the program that came with the motherboard, I use PC Probe II and Speedfan (my mobo is Asus M2N-E) both programes indicate the same temp...
Check out
this thread too.. I hope that everything will work out.