10.5 Server to 10.6 Server upgrade issues

I had two strange issues when I did my 10.5 to 10.6 upgrade. I had a backup of my 10.5 Server. It is running AFP, DNS, Open Directory, and SMB. I erased the hard drive and installed 10.6 clean, when the migration assistant came up I selected my backup and it migrated my settings over. Once things came up in 10.6 I checked things over and all looked well. All my settings and users had transferred over, their home directories are on a SAS connected RAID and shared out over AFP. So I went to a 10.6 client machine and tried to log in and got an error, "can't login at this time... an error occured" So I tried a 10.5 client machine and got the same error. On both machine I removed the server from Directory Utility and re-added it, it connects fine with a green light. But still can't log in. I check the Open Directory settings and LDAP, Password Server, and Kerberos are all running and the LDAP search Base and Kerberos Realm look correct. I reboot the server to see if it is just some weirdness, but even after a reboot I can't log in from a client workstation. SO I boot back off the 10.5 backup and all goes back to working normally. So I clone 10.5 onto the boot drive and run a straight upgrade on it, unfortunately it had exactly the same problem. So I am stuck at 10.5 till I can figure out what is causing the OD login issue. On a side note when booted into 10.6 Server, if I tried to do screen sharing to the server from 10.6 client or another 10.6 server bonjour screen sharing would not work nor would the short DNS name. I could only connect using the fully qualified DNS name or the IP address. Yet I could do AFP, ssh, etc using bonjour name or short DNS name. If I did screen sharing from 10.5 client or server to 10.6 Server everything worked normally???