My Mettler Toledo 8442 scale is giving me this error message; error 200 database error?

That usually means the database file has become corrupt (usually because the machine has been unplugged for too long). You will need to do a RAM (memory) clear and re-program it. I don't have the book for this model but one of the users has it here:

http://the-checkout-tech.com/manuals/scales/Mettler_Toledo_8442_Technical_manual.html

Registerman
January 2013