Sessions disappeared in the GDM menu!

[Adam Funk <a24061@yahoo.com>]

I just did an apt-get upgrade and now the GDM sessions menu has been cut
down to Default (which is KDM), Failsafe GNOME and Failsafe something
else.  /etc/gdm/Sessions still contains all the previous launch
scripts:


/etc/gdm/Sessions $ ls -l
total 24
-rwxr-xr-x    1 root     root           34 2003-10-23 10:25 Debian
-rwxr-xr-x    1 root     root         3089 2003-10-23 10:25 Gnome
-rwxr-xr-x    1 root     root          115 2004-01-30 04:05 KDE
-rwxr-xr-x    1 root     root           76 2004-01-23 15:37 WindowMaker
-rwxr-xr-x    1 root     root          102 2004-03-09 18:40 Xfce4
-rwxr-xr-x    1 root     root         3859 2003-10-23 10:25 Xsession
 
but GDM is ignoring them.  Why, and how do I fix this (preferably
quickly)?

Thanks,
Adam