I am having difficulties associating a specific file type (.dwg) with the correct program (Bentley Microstation). At some point, the file association switched itself from Microstation to Adobe Acrobat Distiller. I reset it in the Folder Options/File Types interface to the path for Microstation (right clicking and using "open with..." would not reset the association).
Now the icon is correct, but when I double click on the file, Microstation opens and returns the message "File [path] does not exist." I can open the files by starting Microstation and using File/Open.