Just closed DW, deleted the cache file, re-opened DW, opened the CSS MenuWriter settings, clicked "Finish" and the same error is appearing.
Even if I don't edit anything, and just click "Ok" I get this error.
I don't see how the configuration folder could be corrupt because I clean installed version 2.0.3 and everything was working fine up to that point.
Any other ideas? Really appreciate the help, thank you.