|This sounds like a Windows virus. Try booting up in safe mode. Hold down F8 while your system is powering up. When you get to the 1st menu, select "safe and networking" mode. This normally ensures that no non-Microsoft programs automatically start with Windows. |
Assuming that the pests did not start this time, run a full scan with your installed anti-virus program (clean/destroy any pests that are found). Also, run a full scan with your installed anti-spyware program. That usually does the trick.
If that didn't work, the pests can still be eradicated by taking out your hard drive, attaching it as a secondary drive on a healthy system, and running anti-virus scan on the problematic drive from the healthy system.
I've done both of the above at times with success.