Failed assertion in virtualbox-ose 4.1.18

[Kamil Choudhury]

Hi all: 

I've got a troublesome Win2K8r2 guest on a Virtualbox/FreeBSD 8.3-RELEASE 
AMD x6 host. 

The guest is running headless, with two SATA discs, 2 cpus and 6 gigs of RAM. 

Special consideration: I compiled virtualbox using the --disable-hardening compiler option. 

My port options were: 

[X] DBUS            D-Bus support                      
[X] DEBUG           Install debug symbols              
[X] GUESTADDITIONS  Build with Guest Additions         
[ ] NLS             Native Language Support via gettext
[ ] PULSEAUDIO      Support PulseAudio sound server    
[ ] QT4             Build with QT4 Frontend            
[X] UDPTUNNEL       Build with UDP tunnel support      
[X] VDE             Build with VDE support             
[X] VNC             Build with VNC support             
[ ] WEBSERVICE      Build Webservice                   
[ ] X11             X11 support                        

The host starts up okay, runs for a period of ranging from half an hour to five hours, 
and then invariably crashes with the following error in the log: 

00:35:50.612 !!Assertion Failed!!
00:35:50.612 Expression: pTimer->enmClock == TMCLOCK_VIRTUAL_SYNC ? enmState == 
TMTIMERSTATE_ACTIVE : enmState == TMTIMERSTATE_PENDING_SCHEDULE || enmState == 
TMTIMERSTATE_PENDING_STOP_SCHEDULE

Googling doesn't seem to reveal a great deal, and I have not yet done a source dive to 
figure out what's going on. It's especially perplexing given that there is another 
Win2K8r2  VM running flawlessly on the same host (albeit with 1 CPU, 2 gigs of RAM and 
1 SATA disc.)

Any assistance would be greatly appreciated. Has anyone ever seen anything like this? 

Thanks, 
Kamil