well maybe you misconfigured your video card. Run xf86config. Its a text based environment and re-do the configurations. It may help. be sure you know what chipset your board has. I think yuo can also choose and "general" chipset that should work on most cards. If you can put it to work, then use XF86Config. This is a graphics interface, and I find it mutch easier to use, to tune up X display.
you dont need to rebbot every time. make psux and find the xdm daemon. kill all xdm related processes. when you are up to try something run startx regards
