Mono doesn't work very well. Try installing dotnet20 with winetricks. You will have to create a clean wineprefix for that. If you don't have any other apps installed in Wine that you want to keep you can just delete ~/.wine and start over. If you do have other apps, create a new wineprefix following the instructions here: http://wiki.winehq.org/FAQ#head-faf9617c53607e583f6e6ff70a4ac9522d490faf
