I just had a bit of a Google, and the received wisdom seems to be to delete the inbox.dbx file.
Easiest way to locate it is to click the Start button, select search and type in 'inbox.dbx' (you will have to enable search in hidden files or folders)
As before, take a backup then delete it.
As long as you do this sober, and take a note of where the original files were located (in case you need to paste back your backups) you'll be fine.... honest
