The "VMX root mode" problem is known since at least 2008. On Linux hosts it's been possible to disable whatever puts the CPU into that mode, but that may be harder on OSX.
Thanks. Well that certainly makes it look like a VB issue rather than Apple, doesn't have an impact for me but I can imagine there's some very stressed developers this morning.
There's more information here: http://www.virtualbox.org/manual/ch10.html , "Hardware vs. software virtualization" and forward. If I'm reading it right, it might be possible to run VB in software virtualization mode even with the new firmware.
