Download and install the latest patch, which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.
- Download Management Studio Express
- Connect to the FE7_MSDE instance
- Add the user and give them Public role rights
Note: Detaching and re-attaching the database will reset the password and cause the error to recur. Repeat the above steps to correct the error.