Very sorry about the problems Mailwasher Pro is currently having, (all mail checks fail, corrupt database messages etc) our developer is looking into what is happening now, unfortunately the problem occurred on Sunday afternoon when no-one was available to look into what was happening, was entirely unexpected, and we're not even sure how its possible as yet.....!
Still currently unsure of the cause, but hope to have it resolved soon.
In the meantime, options are to either not use MW for the meantime, OR, use an older version as below.
If you wish to to do this:
* please uninstall your current MWPro,
* cancel the question asking why you are uninstalling
* click YES when asked if you wish to save your user data,
* install this version:
http://cdn.firetrust.com/downloads/mail ... _12_25.exe
And it should work fine.
If you could also please do not respond to this unless still having problems with the above version and that'd be appreciated.
Cheers!