Hm. Okay. So it obviously understands the video card's graphical modes at some level. Let's try reconfiguring X the standard way: try running "xorgcfg". If that doesn't work, try "xorgconfig". Both will create a configuration file. The output should tell you where this file is saved. Assuming one of them seems to work properly, then try to run "X -config <configfile>". You should see a screen with a black and white texture and a big black X-shaped cursor. If so, everything is configured properly. Exit by pressing Ctrl-Alt-Backspace. Then try startx again.