As a precaution I moved this to Malware Discussions.
Don't click on anything that may be displaying.
If you can, power down & reboot into Safe Mode by tapping F8 repeatedly while booting up, then try to invoke System Restore to before all this started.
SR is found in Start > All Programs > Accessories > System Tools. or you can invoke it by going to Start > Run and typing rstrui and clicking OK and hitting the Enter key.
You don't say what operating system you have but in Vista and Windows 7 simply type rstrui in the box above the Start button and it should appear in the space above, that also will start System Restore.