Phenom II Quad procie Problem. slowdownn

[jprovido]

Hi Tech imo. ive been experiencing this problem for a couple of weeks now. sometimes when i turn on my pc. after a few minutes. it will slow down. one of my 4 cores(usually the 4th and 3rd core) will be at 100% load. but when i restart my windows it will return to normal? what should i do to resolve this? it happened about 5 times for the last 3-4 weeks.