Hi from Berlin,
I just had a rather negative experience with one of my favorite tools: CCleaner.
I always use the zip version, and today a new version came out. (http://www.piriform.com/ccleaner/builds). As always, I set it up over my old version and ran the cleaning function.
All of a sudden, I noticed it had wiped out many MBs of data from MWP, specifically from the folder that holds the contents of the Recycle Bin

Fortunately, Piriform, the company that makes CCleaner, also makes an undelete program called Recuva, with which I was able to fix pretty much everything.
My tip: If or when you install a new version of CCleaner, look under the "Applications" tab in the "Cleaner" section, and make sure MailWasherPro is unchecked.

Hope this helps.
Best regards,
JoeG