After the FreeBSD VM crash, file system in VM got rolled back to some old previous state causing data loss

[Yuri]

I hit this unexpected problem: my host had an ungraceful shutdown while 
FreeBSD 9.1 STABLE was running in the VirtualBox VM. After reboot of the 
host and VM, local ufs file system was missing all recent updates for at 
least 20 hours (!!!)
My question is, how is this possible? Is this related to journaled 
soft-updates which were enabled in VM?
Losing data looks like a critical issue. I had a backup outside VM so no 
real data loss for me, but this is bad.
Fedora VM, that was shut down in the same way didn't suffer from the 
same issue (local ext4).
Host shutdown was caused by the frozen Xorg, I had to kill it and 
reboot. VirtualBox processes got killed in the process.

Yuri