I did a GUI install. I have a rivaTNT based card ( Diamond Viper 550AGP ). It was recognized as "rivaTNT". After I changed the video memory to 16 MB I clicked on "test". Before the new X server was displayed, there were some dark vertical lines of different width on a black background. They also appeared when returning to the anaconda screen. The anaconda screen was all screwed up ! The standard X11 background pattern was displayed, but in green/black instead of black/white. The only other objects on the screen were the pointer and the radio buttons and the arrows of the NEXT/BACK buttons. No text , no anything. The buttons were still responding , at least the NEXT and BACK. At this point I switched to VT1 ; black screen. VT2 also black. VT7 ( still looking green and bugged ) , back to VT1 , now it's OK. Then I wen't to VT7 and clicked on BACK until I got to the Timezone Selection. There by moving the pointer over the world map ( which was not visible ) caused it to be redrawn , mostly around the green arrow that is drawn when you move the mouse over the map. This may be several independent bugs , but I'm filing only one bugzilla entry.
Given how late we are in the development cycle for Winston, I really don't think we're going to be able to fix a driver issue like this before release. The best thing we can do is work on it for the next release, or if possible, issue an errata with a driver fix when it's available.
Still there in RC1
This is certainly an X server issue. Some hardware does not respond to the test sequence well. We have tested cards based on the same chipset without experiencing this problem. Its a card by card issue, and can only be addressed by the X server author.