It's a fake/scam program designed to hijack your computer and get you to pay to get control back. Of course don't ever in a million years give any credit card numbers or money to these scammers.
Personally I would just format/reinstall but you probably don't want to go through with that so I would suggest you first try to run
SUPERAntiSpyware Portable Scanner. If that doesn't work give
Malwarebytes' Anti-Malware a shot. You may have to download them from a different PC or rename them.
If you're still stuck maybe this guide can help.
Total Win 7 Security Analysis and Removal -Google is good.
You might go through
Gizmo's Freeware Security Wizard for advice and software to prevent such problems from reoccurring.