Please do not start multiple threads for the same problem click here
It must be one of the programs that is loading at start-up. You will need to find out which one by a process of elimination.
Start, Run, type in
and click OK.
Look on the startup tab. Disable each program one at a time then reboot. If the problem is fixed you've found the culprit. Otherwise run msconfig again, re-tick that one and untick another etc. etc.