Restore Default File Associations

Sounds like you have been tinkering with settings, did you alter any regestry keys? Delete anything?

If you need to do a file association in Vista, see This.

Start > All Programs > Default Programs.

Then you have:

• Set your default programs

and

• Associate file type or protocol.

Restore The .exe File Association In Windows Vista, After Incorrectly Associating It With Another Application.

I discovered a possible fix Here.

Vista File Associations Lost.

For one of the various pages about registry virtualization, see This.