VirtualBox-3.0.12-54655-Win

I'm running 32-bit Windows XP with CentOS x86_64 in a VirtualBox-3.0.10-54097, with an intel Core 2 Duo (VT-x support enabled via BIOS).

I just tried to upgrade to VirtualBox-3.0.12-54655; but, the CentOS box wouldn't even start up! I even tried live CDs!

Here's the evil error:
NMI Watchdog detected LOCKUP on CPU0

Maybe there's a compatibility issue with the kernel?

$ echo "`cat /etc/*-release` `uname -m` : `uname -sr`"
CentOS release 5.4 (Final) x86_64 : Linux 2.6.18-164.6.1.el5

Everything went great with my i386 version, though...

$ echo "`cat /etc/*-release` `uname -m` : `uname -sr`"
CentOS release 5.4 (Final) i686 : Linux 2.6.18-164.el5

I don't know...