MailWasher's database can become corrupt if the computer shuts suddenly down while writing to the database.
If your MWP.db3 database is corrupt, (this holds your learning settings, and blacklist/friendslist), if you can start MWPro and it will run OK, click Help>>User files in MWPro.
Minimise the folder that opens.
Click File>>Exit to close MWPro.
Maximise the folder, then open the Cache folder.
If not, please browse to:
C:\Users\[your logon name]\AppData\Roaming\Firetrust\MailWasher\cache
(This folder is actually hidden, so you may need to enable Windows to show hidden files and folders under,
the Windows Control Panel, Folder Options>>View Tab>>Select, Show hidden files and folders.)
Then, (With MWPro closed) rename the MWP.db3 file to MWP1.db3 and restart MWPro, see if it starts OK then.