The server was unable to save the form at this time. Please try again.

Now here is a strange one...

Scenario

1. Create a new Document Library accepting all defaults
2. Add a document to the library
3. Edit the properties of the document and save.
   RESULT: The server was unable to save the form at this time.  Please try again.
4. Enable 'Manage content types' in the library setting.
5. Add the 'Link to a document' content type.
6. Edit the properties of the document and save.
   RESULT: Fixed