1) Backup your grades to a new diskette
2) Choose Repair / Optimize from the Tools menu on the 1st Class 
GradeBook main screen.
3) Re-install 1st Class GradeBook.
4) If you do not have the latest version then download and 
install the latest version.
5) Please email a copy of your database to us along with a 
detailed explaination of the problem. Here are the instructions 
on how to do this:

http://www.1st-class-software.com/cgi-bin/fom.cgi?file=104