I set up a dual boot system with Debian 3.0r1 and XP Professional and started learning a bit about the the command line and how linux is set up. I wanted to have a look a some GUI stuff, so I installed XFree86 using apt-get install x-window-server. It prompted me for some configuration settings, which I entered in, and then rebooted. When I rebooted, I was still at the command line, so I tried to start the GUI with both the xdm and startx commands. They seemed to work ok, except for the fact that it would stop at the end of the start-up sequence and say something like "Screens found, but no useable configuration".

I figured this meant I had stuffed up the configuration, so I tried to reconfigure it the best I could using both xf86config and dpkg-reconfigure xserver-xfree86, but neither made any difference to my problem. The closest I could to it working was by using xf86cfg, which gave me a GUI interface, but I couldn't use my mouse to move around, and when I tried to configure the mouse using the keypad pointer movements, it just crashed.

do this to unsure you didn't forget basic stuff
apt-get install less xfonts-scalable xfonts-base xfonts-pex xfonts-cyrillic xfonts-100dpi* xbase-clients

try startx or your gdm/xdm if you don't login using console.

if it fails check you /etc/X11/XF86Config-4 for the mouse and the driver used

do also
less /var/log/XFree86.0.log