You are not the only one with this problem. I have some new built PCs in my classroom that have ASUS A9250 AGP Video cards. The intent was to demonstrate how PCs with only a CD-ROM and no Hard Drive could still be used to access the Internet using the Knoppix disk.
I encountered exactly the same problem as you, and have been unable to troubleshoot the problem so far using cheat codes.


Monitor (tried several different models) and video card characteristics are recognized during the boot, and I can complete a boot to Mode 2. Any attempt to initiate startx results in black screen.

A significant commonality is that both of the Video cards are using ATI technology.