Why any running process starts to load the processor?

Question

Computers

I don't understand what happened. I start the PC, everything is fine, after 3-4 minutes, what happens to the PC. When you start any program, be it a browser or AIDA, the processor starts to load at 100%. After 20 seconds everything is fine again. What to do? Windu reinstalled, downloaded the image from ms. The processor does not trot, the temperature is 40-50 degrees, everything is fine.

Answer 1

I am sure that this is not one of the first four reasons named by Igor Karpinsky , but the fifth one is 100% :)
1. try turning off the antivirus for a while;
2. check the status of the disk.