I would do the repair of the PST file. See if this helps: http://www.officeforlawyers.com/outl...ol.htm#SCANPST

I did and after about five runs, it said it had gotten rid of all errors.

Still the same: cannot delete or move folders, error message: "folder is full", even though I have <shift>-deleted loads of messages, so there should be ample room in the .pst file.

It's possible that even after 5 passes of SCANPST that the PST file is just too corrupted.

You might have to create a new PST file, copy only the items you want to keep into it, then set that new PST file to be the default and close/delete the old PST file.

http://www.officeforlawyers.com/outlook/tsol.htm

I'm afraid so, but there si some additional complication: I use Business Contact Manager.

I will first try to go back to a backuped version of a month or so ago that did not behave this way and than add the newer mails in through a new .PST file.

I realize I may run into these issues later again, but I will keep my file a lot smaller from now on.