Hehe, registry cleaners

is that a euphamism for formatting your drive and reinstalling your OS ?
I used one othe those things at work a while back; fortunately I made a system settings restore point before I did anything, because after I ran the registry cleaner, the main program I use at work (AutoCAD) and other programs like office etc had parts missing and kept crashing loads :P
Maybe I did something wrong
Not ventured anywhere near a registry cleaner program since, unless I'm using window$ 'regedit' and following detailed instructions from symantec security response