[Fedora-xen] Strange video problem with Xen kernel and undocked laptop

[Michael DeHaan]

Computer:   IBM T43
kernel:    2.6.19-1.2895.fc6xen

When docked, the laptop seems very happy, and I can use X/Gnome/etc fine 
... undocked, the entire screen goes black right after logging in via 
gdm and I can't even switch to a tty.   Booting a non-Xen kernel allows 
full use of graphics, and I can find no relevant enteries in 
/var/log/xen/* that indicate what might be going on.

Any ideas or has anyone else experienced similar?

--Michael