Ok, but because the any changes to the Registry can cause problems to your system, do not even try until you understand how it works.
GUID numbers are the ones between the {} and Microsoft loves them......
If you want to try the registry editor to check the keys I mentioned, use the Winkey+R to open the Run dialog. Type regedit and hit enter, then accept the permission upgrade box.
You can probably find several sites that discuss the registry and how to use regedit.exe, so you might want to find one of those. But the registry is divided into keys. The higher order ones deal with different parts of the system. So, on the second key I gave you, going to the HKEY_Classes_Root and expanding it to the CLSID key and expanding it to the {D969A300-E7FF-11d0-A93B-00A0C90F2719} key.
You can also do a search for things, so try to copy and paste the GUID number in the Edit/Find window (CTRL+F) and search. The bottom of the windows has a listing of which key you currently have selected
Then do the same thing with the other key and confirm both are present as set as described. If one is not, hopefully we can correct the problem... Play with it if you want to see how it works. If you can verify a problem, it might be as easy as double clicking a file to correct.