I don't have either exceed or AIX so I'm really flying blind here. Sign into a system that is working well for you and type "ps -f". Do the same thing on a system that isn't working well. If your shell shows up with a CMD field like "-ksh" on the good system while it's something like "ksh" on the bad, then the problem is that xterm is not being invoked in login mode on the bad system.

If this is the case you will need to reconfigure exceed to run the command "xterm -ls" on the bad system instead of "xterm" or "xterm +ls".