JohnJ --
The general process is this:
1. Save the corrupted file as an .xml file and close the file
2. Ask your Project Server administrator to delete the project from the
Project Server database
3. Open the .xml project file
4. Click File - Save As and save the file as an .mpp file
5. Import the .mpp file into the Project Server database using Tools -
Enterprise Options - Import Project to Enterprise
Refer to the following FAQ for the steps needed to delete the project
without deleting its SharePoint subweb:
http://www.projectserverexperts.com/Shared Documents/DeleteProjectWithoutSubweb.htm
Hope this helps.