Oh boy.
Well, I would start out with the editor directories and files within the /mambots folder. In fact, I would see if all your directories and files have the correct permission settings.
The problem I've come across is that, sometimes, there are directories and files outside of the "problematic" directory that's causing the issue. The best thing to do is follow any JavaScript and/or PHP errors you might be getting and check the permissions on the respective files. For example, if /tmp needs to be writable because Mambo is trying to temporarily place an image or whatever there, that could be a start.
HtH!
Regards,
Kory