Thanks for the response. The logon app looks like the standard Debian one. It has the Debian logo and provides textboxes for username and password. But no way to choose the desktop to start up. I guess this logon app is called xdm?
My system is pretty basic. I installed WindowMaker, Synaptic, KDE, Gnome, and Mozilla. I installed KDE before i installed Gnome.
If this is a configuration issue, no sweat. I can locate and edit text files. I just need to be told where to look and what to change.