Problems with GDM - graphical greeter gone

[Mark Nixon]

Until recently, I had Bluecurve as a graphical greeter. After I updated
KDE to 3.3.2 a few weeks ago, it was gone. All I get is a chintzy little
black and white login. I've just updated to 3.4, and it's the same.

I've tried GDMsetup, but it doesn't change a thing. I've obviously
borked something, but I can't figure out what. Is this an XWindows
thing?

Mark