Using safe mode
Most of malicious processes are inactive when PC operates in safe mode with networking. To reach safe mode with networking, do following:
Reboot
Press F8 early on (you can press F8 couple times)
Choose Safe mode with networking (preferably) or safe mode from menu
On success you should not see any alerts that bother you under normal mode
Killing processes using task manager
The benefit of using task manager is that you do not need to download anything. Task manager is present in all windows computers, though it might be disabled...
