what.. have you fried something. Maybe your CPU is dying.. sorry to say something soo bad. if so you can upgrade like you've wanted to. If thats teh case can I have your old one just for fun.
Try hitting the cmos reset.. then that will set everything up the default way.. then you will see it downclocking very low, then jumping back up to 2.4 GHz. try that. but then you'll need to readjust everything. so write it down