I updated to LMDE 1204 yesterday, and got some problems with the usage of my external monitor.
If I leave the monitor plugged in, X does not start, I get a black screen with a blinking cursor.
Unplugging the monitor and then boot, starts X. I get the login screen. If I plug in my monitor at that time, X restarts and I get again the login screen.
I can work with both screens, but if I unplug the monitor, switch it of, or let the monitor go to sleep, X again crashes and I get again the login screen.
I'm using a laptop with an Nvidia 9600GTM and I'm using the nvidia drivers from the update 295.20.1.
Everything has always worked perfectly before updating.