Double click on .doc opens Word but not the document

I've finally found an answer that works.

^{Involves editing registry. Make sure you don't delete the wrong bit or you could wreck your machine. Not my fault if this happens.}

• Check that Word is closed. Open RegEdit and find:

  HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Data

• Delete the whole "Data" folder and subkeys.

• Thats's it!

This happens sometimes when you already activated the document preview feature and want to open it in the "real" application (Word, Excel, Powerpoint etc.).

I know of no way to prevent this from happening, except not to display the attachment in the preview mode first.

Same problem occurs also with Windows Explorer's Preview pane.

• Go to Help → Detect and Repair
• Check "restore my shortcuts..."
• Uncheck "Discard my customized settings..."

Had the same problem on a couple of client PCs (probably after office update installation). Only solution was to re-associate Word with it's file types by running the following command (needs local administrator privileges):

C:\Program Files\Microsoft Office\Office12\WINWORD.EXE /R

(change the path if your office installation folder is different)