I don't think you can simply run the backup utility and restore the 3.7 Access database to version 5. If so, why would you need to do the migration?
Jack, while you can update from 3.7.15 to 5.1, have you tried (just for kicks) to install 4.0 and upgrade and migrate to it, run its database tuner, then upgrade from 4 to 5?
Support is open until 9 am EST, so you should be able to get some help.
