Aha, what you have is a Rogue Virus. They're very dangerous, as they can remove all of the money from your credit card. They auto-install a program on your computer called 'windows security'. The title may sound very trustworthy and microsoft-related, but trust me, its a ticking bomb, ready to steal your money. Its very clever, as it explains that all of your .exe files and virus checkers have been attacked. It says 'purhcase anti-virus pro for $19.95. If you buy this, (DONT!!!!!) it steals all of the money off your already entered credit-card details. Don't fret though, this is the way I reverted my .exe files to their original state and got rid of the virus.
1) Insert a pendrive in 'windows safe mode' and retrieve all of your important files off your account,you do this by: Click on my computer, click on Users, then click on your account name. Then you should be able to retreive any photos, documents, videos, .exe(s) etc, you would like to keep. (copy them onto a pendrive / external hard-drive)
2) Now, while youre in 'My computer/ Users' Click on your account and delete it. If it is your only account, create a new (administrator) account. This can be done in the 'control panel'. This should destroy the fake anti-virus program and all of its other affected areas.
3) Now, reboot, and go on your spare / other administrator account (this should not be affected at all) and load all of your files back (and install an anti-virus program)
4)Now, in your recycle bin, there should be an folder saying the name of your old account you have just deleted. As quick as possible, delete that folder. This should take a while.
5) Load back all of your retrieved files off your pendrive / external hard-drive.
And enjoy your fixed computer / laptop!!!
Reply if this didn't work,