Use this command to open the folder that has your Realm Works master folder:
Code:
explorer "%APPDATA%\LWD Technology, Inc"
Rename the "Realm Works" folder to something else (and keep it in case the RW team wants to see your problem database) then start Realm Works again and let it download from the server or restore from your backup.
(Alternatively, download the Realm Works Locations Application linked in my signature, which has buttons to do this for you.)
FWIW, Firebird is the name of the database engine used by Realm Works. By renaming the folder and letting Realm Works create a new one you're testing to see if your master database or one of the support files became corrupted. Uninstalling and reinstalling RW doesn't do anything to your existing database files; you have to mess with them yourself.