This belongs in the Alternative OS (Linux) forum.
For now, try editing your xfree/xorg config (most likely in /etc/X11/XF86config ) and changing your video cards device driver to a generic one, try "vga". The easiest way to do this without a GUI is to run the auto configure, by typing at the console:
X -configure
If that fails to properly give you a setup, try running the guided setup, which is xf86config, most likely started like:
/usr/X11R6/bin/xf86config
Choose conservative refresh settings and the generic vesa video driver.