I have managed to get Knoppix 6.7.1 to behave as well as 6.2.1 did on my hardware.

To make this happen I had to:
* pass "xmodule=fbdev" or "xmodule=vesa" on the kernel command line; the nv and svga xmodules didn't work
* turn off "Green LAN" on the Realtek onboard NIC in BIOS
* disable IPv6 globally via entering "echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6" in a terminal as root, and manually in Iceweasel by going to the "about:config" page and setting "network.dns.disableIPv6" to true

The Knoppix NVidia driver is definitely broken, at least when used on a EVGA 01G-P3-1556-KR GeForce GTX 550 Ti (Fermi) FPB 1GB video card. This is the only thing that seems to be unique to Knoppix. I'm seeing the Realtek and IPv6 problems on a Mageia live CD.

The IPv6 problem is especially aggravating and difficult to figure out. There seems to be no way to do disable it at boot. Disabling it globally stops *most* programs from trying to use it, but Iceweasel (Firefox) will continue to try to use it, even if restarted after it's disabled, until you turn it off in the "about:config" page. While some people merely reported slow networking with it enabled, I literally could not connect to anything with most graphical programs with IPv6 enabled, unless I used the IP rather than the DNS name. The connections always timed out.