Sorry to hear that. After you quit though, the files are still in the Shared folder, right?

Hmm. Go to Control Panels->General and see if "protect System folder" or Protect Application Folder" is checked.
If your shared folder is inside either, you can't write to it.
[edit: I just checked and my OS 9.2.2 doesn't have those options--they were in OS 8.6]

At least now you are entitled to Pro Support (email them your description and tell them you've tried to work it out in the forum--maybe you'll get an answer).

the only other things I can think of are not too common--i.e

Try setting the number of days to keep incompletes (Tools->Options) to some other higher number. The default should show 7. This works for some other problems.

You can rebuild the desktop and hope that will somehow caused the Shared and Incomplete folders to be "recognized"

Lastly, try looking at your Control Panels->Extensions Manager, and turn off any none OS 9 extensions. Extension conflicts can cause all sorts of problems, but I've never heard of one doing what you describe.