Microsoft Access databases can become corrupt, or damaged.  In most cases, this is caused when a database operation is interrupted by the web server or there is a filesystem problem.  It is not usually related to any PDshop scripts.

If you have the Microsoft Access 2000 (or XP) program you can run the "Compact & Repair" utility to repair the database.  It is also recommended that you run this utility once a  months (as a preventative).