freebsd stable - Jul 2017 - [REVISED] Panic with FreeBSD 11.1-RC2 VM-IMAGE when starting vboxservice

With latest VM-IMAGE (vmdk) for 11.1-RC2 system panics.  I haven't been able
to process the panic completely, but the backtrace looks mysteriously similar to
those provided with PR219146.


Initially, the VM-IMAGE booted just fine.  The VM-IMAGE is then configured as a
VirtualBox client.  The panic occurs on subsequent reboots when attempting to
start vboxservice.


Additionally, during the custom configuration process, lsof hangs for more than
2 minutes each time that it is invoked.


Please let me know exactly what information is needed to correct this problem. 
I will be able to provide that information no later than Tuesday morning.


Thanks, in advance, for your assistance.


David Boyd.