Display issues...
 

I just installed Mandrake 9.0 and the installation seemed to go fine (I choose to use Gnome for my graphical interface) , but when the system boots the display is all wrong. After the boot messages the screen blanks, then changes to a screen with interlaced multicoloed lines on the top third, blank in the middle third and what looks like a screen test on the bottom half (vertical colored bars showing 65 million colors or some such) with the watch icon as the mouse pointer. Or other times I will get a blank 2/3 screen with solid blue at the bottom with the watch mouse pointer. It does not seem to matter how long I let it sit, the system remains the same. I am running an AMD k6-2 500 Mhz with 320M ram, an ATI radeon 7000 graphics card. Any help would be greatly appriciated.