Sounds like your Xconfig file is not using the correct driver. depending on your X server you need to look for Xorg.conf or Xfree86.conf. They are usually located in /etc/X11/
In the file you should look for a line that looks something like this
Code:
Section "Device"
Identifier "VideoCard"
Driver "vga" <----Try vga or vesa vesa probably be best
VendorName "Generic"
EndSection
I hope this helps you