This error code means that the document is somewhat messed up.
Do you want to do a Save as… or does it work with Save (try that on a copy). Or does the error pop up already when the document is opened?
When it pops up when the document is opened, try getting another copy of the document.
When you can do a Save, but not a Save as…, it is kind of normal, ynd you can overcome it for Save as… by boing into the Acrobat/Reader Preferences and deactivate the "Save as… optimizes for fast web view" option. The reason for the error in this case is that when optimizeing for fast web view the internal structure of the document gets changed, but in your open version, the pointers are still set for the original version. So, when the document refreshes, the pointers point to wrong places.
Hope this can help.
Max Wyss.