Ok, my fault. BS is a standard command in mIRC with networks that support BotServices. Since I don't use botservices, I didn't realize that.
Ok, perhaps you can tell me what exactly is running when you hit cancel? Is it still doing a command, but giving an error?
Such as *BotServ* Channel ____ isn't registered. or something similar?
Or is it doing something else? I'm thinking it's one of two things... either the BS commands can't be cancelled after started without rewriting the script to handle entering the channel name BEFORE calling the BS command, or it's the "erase" command that's running.