The new 3.4, unlike 3.3 and earlier, does not shutdown properly on my system, either from CD or HD install, for both new and old kernel.
I have read elsewhere on thsi forum that replacing KDM with GDM might would help. But it didn't. Logging out does not work, nor using the command line. Knoppix seems to unload itslef, but the system is left running. It is the same for shutdown and reboot. The only option left is to hard shutdown the computer.