Using the generic VESA graphics driver

If the X server (which provides the graphical user interface) fails to start up, chances are there's a problem with the driver for your graphics chip.

You can fall back to a generic driver that works for almost all cards (but is rather slow, since it can't make use of hardware specific optimizations) by editing the file /etc/X11/xorg.conf.

In that file, locate a line saying Section "Screen".

A couple of lines below that, you'll find a line saying Device "something". Change that line to read Device "Generic VESA SVGA".

Save the file. You should now be able to get into the graphical user interface.