Sometimes you can not associate a program with an extension in Windows 7


Symptoms


You may not be able to associate a file extension to an application in Windows 7.

Cause


This may occur if the program you are attempting to associate with is not registered correctly.

Resolution


Follow the steps below:
1. Type "regedit" in the Run line or from an elevated CMD prompt.
2. Navigate to Computer\HKEY_CLASSES_ROOT\Applications and find your .exe name.
3. Navigate under its name to shell>open>command.
4. Under Default, make sure the application location points to the actual location of the executable.
5. Press OK and then try and reassociate the file type as you normally would.