If I change the number of CPUs from one to two in Oracle VirtualBox 4.0.12 on a Windows 7 host with an Intel E8400 Core2Duo CPU then Knoppix 6.7.0 starts as fast as usual. It seems that the update of the progress indicator induces a deadlock.

I think that a new cheat code 'noprogressbar' could be useful on some systems.