Enable SMB for AD Users

We have a magic triangle setup with portable home directories. No data from the homes is synced except for workgroup settings.

Now my problem is I cannot enable smb on my users (even those who are in the admin group set in directory utility). In System Preferences/sharing/file sharing I always get a “invalid password” message. AFP works fine but is not routed outside our network and ftp is not an option. By the way, no such problems for local accounts.

Another problem is that when people are not connected to our local network, the login time at startup or from screensaver takes almost forever and usually is denied. My only fix is to have the user disable airport before login out, but no idea about a workaround when authenticating from screensaver. I thought that whenever the active directory is not accessible authentication would be done locally. What am I missing?

The users that are concerned with this are all on 10.5.8 or 10.6.2.

Any help would be very much appreciated! Thank you!

kodex