When joining a domain via YaST, some needed packages are installed. When configuring mountpoints via YaST for the Active Directory Domain, the pam_mount need to be installed. Actual result is that when pam_mount package isn't installed, you configure the mount point and save them. Then, come back to the window, they disappeared. As soon as pam_mount is installed, all is good. Maybe a dependency is needed ? This is on OpenSuSE 11.2.
As this is a distro packaging issue, please open up a bug on bugzilla.novell.com