[xen-tools-discuss] Screen terminates immediately (xen-shell)

[doug at wandell.com]

After installing xen-shell and configuring a test user, when I ssh in  
as that user, I am immediately disconnected with the message:

[screen is terminating]

System is:
[root at osiris log]# cat /etc/redhat-release
CentOS release 5.2 (Final)
[root at osiris log]# uname -a
Linux osiris.wireandlight.com 2.6.18-92.1.10.el5xen #1 SMP Tue Aug 5  
08:11:18 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux

And is fully up to date.  I don't see anything in syslog, can someone  
tell me where I might look for clues?
DW