This question is an exact duplicate of:
For some time now when I click Open with from Windows Explorer's context menu I'm getting this error
This file does not have a program associated with it to perform this action. Create an association in the Set Associations control panel.
instead of the standard Choose Default Program dialog. I'm getting this error no matter what the extension of the selected file is (as long as there's Open with option for given extension; some extensions do not show this option). How can I fix this?