FreeBSD amd64 guest sometimes hangs during boot

[Yuri]

This happens in ~<10% cases. Guest hangs right after "Welcome to 
FreeBSD" screen (with 1.-7. boot options), after cursor jumps to the 
bottom left corner of the screen and is supposed to be "spinning".

There is (probably unrelated) error in the log file.
VirtualBox process consumes 100% CPU when hanged.

virtualbox-4.2.6

Yuri


---log excerpt---
00:00:01.724321 Using XKB for keycode to scan code conversion
00:00:02.078068 ERROR [COM]: aRC=E_ACCESSDENIED (0x80070005) 
aIID={db7ab4ca-2a3f-4183-9243-c1208da92392} aComponent={Console} 
aText={The virtual machine is not powered up}, preserve=false
00:00:02.133508 SUP: Loaded VMMR0.r0 
(/usr/local/lib/virtualbox/VMMR0.r0) at 0xffffffff8265b020 - ModuleInit 
at ffffffff826914c0 and ModuleTerm at ffffffff82691450
<...skipped...below is the end of the log up to the point of hanging>
02:53:03.669889 PIT: mode=2 count=0x10000 (65536) - 18.20 Hz (ch=0)
02:53:03.670373 Guest Log: BIOS: Boot : bseqnr=1, bootseq=0032
02:53:03.670953 Guest Log: BIOS: Booting from Hard Disk...
02:53:49.956882 PIT: mode=2 count=0x10000 (65536) - 18.20 Hz (ch=0)