Unable to cancel running command and start a new one

[nathanletwory (Nathan 'jesterKing' Letwory)]

See my reply here

Window Closing event is called many times

It is hard to say how cracked versions of Rhino work, we won’t support such versions. You should buy a valid license, and also ensure you are always on the latest service release. That way we have a better chance of finding out what the problem may be if it turns out it exists in a non-cracked version too.