Comment 5 for bug 662288

We are certainly homing in on the source of that problem.

Were you connected to a router when trying to disable wireless in Network Manager? If so, could you try to "Disconnect" (in Network Manager) before you disable? It might make a difference. Not sure.

Also, try a safer way to shut down when frozen (Magic SysRq key+REISUO):
Press and hold AltGr
Press and hold Print/SysRq
now press R and then wait two seconds
press E and wait
press I and wait
press S (watch your harddisk LED, if it goes on wait till it goes off again)
press U and wait
press O (it should power down now)
release AltGr+SysRq

Each of the above letters should start another stage in a controlled shutdown process. The waiting is just to give those processes a bit of time to run. (Documentation is at: http://www.kernel.org/doc/Documentation/sysrq.txt . Not that you have to read that.)