You say you are trying to connect using Frontpage. Do you have the Frontpage extensions installed on the domain that is not working? If not install them. If yes, uninstall them and reinstall them.
Welcome to the forums sk8er0i.
Sorry I don't have an answer for you but I do have to ask that you make sure if you are allowing uploads to your site that you test for extensions and only allow safe file types to be uploaded.
Maybe one of our family members will have some ideas for you.
I would imagine that it was done for security reasons. If you need more information about it please open a help desk ticket. Link above or in my signature.