One of the two users with this problem had an entry under 'Generic Credentials' relating to outlook, I have deleted this entry and asked him to keep...
I'm giving HAP a go, the installation instructions are pretty out of date though so having trouble setting it up in ISS, the latest tutorial doesn't...
I would do as Sukh says and create a new database to move the mailboxes into as this will eliminate the white space. One thing to bear in mind though...
