Sorry to hear that, that didn't help. The problem you are describing is usually due to registry corruption at HKEY_CLASSES_ROOT\.exe and HKEY_CLASSES_ROOT\exefile and is often the result of some type of virus or malware infection. Do you have the option to go back even further with a restore point. If not you will probably need to perform a repair install at minimum or possibly a clean install if all else fails. If you have the resources, to export those two keys from a known good install of your exact version of Windows 7, you could possibly import them into the problem install, but I'm guessing that there is probably other issues that even that, if it would work, would not be able to address.