This problem occurs if you successfully save the project plan offline by using the Save Offline option, and then you unsuccessfully attempt to save the project plan online.
How to Obtain the Hotfix
This issue is fixed in the Microsoft Project 2002 Hotfix Package that is dated September 10, 2003. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
827151 Microsoft Project 2002 Hotfix Package: September 10, 2003
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.