If you intentionally add a %1 to the Open action entry for this file type, a %1 is added to the registry key. If the Open action of the file type is edited and the line is restored before you press OK, a %1 is added to the registry key. This behavior can occur if the Open action entry for this file type ends in %1. After you repeatedly click OK, the file opens. When you click OK on the error message, the message reappears.
If you are trying to open the file from your list of most recently used files on the File menu, make sure that the file has not been renamed, moved, or deleted. Check the spelling of the file name, and verify that the file location is correct.
