This problem occurs when your .exe file associations are broken. This is usually caused by a virus/malware that changes the default file associations in Windows. Follow these instructions to fix this problem:
from one of these two links: Link
1, Link 2
Double-click on exeHelper to run the fix. A black window should pop up. Once the fix is complete, press any key to close.
Then try following the steps in this virus/malware removal guide: http://www.selectrealsecurity.com/malware-removal-guide
It contains instructions that will remove most malware infections.
I hope this helps you,