libvirt users - Nov 2015 - SOLVED: failed to connect to the hypervisor

Ubuntu, for the loss.  Turned out to be an apparmor issue; as I hadn't 
touched the profiles, it must've been something else going on.

-Ken

------------------------- original issue ----------------------------

When I try, I get this:
root@kilo-VirtualBoxHost:~# virsh -c vbox:///session
error: failed to connect to the hypervisor
error: internal error: nsIEventQueue object is null

----------------------------------

The part that puzzles me is that it *used* to work, but no longer.  
"virsh -V" shows me running libvirt 1.2.2, with VirtualBox enabled. 
I'm
running stock Ubuntu VirtualBox v. 4.3.10.  I've rebooted; I've tried 
running it as different users.  Googling comes up with some 
five-year-old Solaris patch discussions.  My 
/var/log/libvirt/libvirtd.log shows stuff like this:
2015-11-25 02:21:39.381+0000: 3893: error : virNetSocketReadWire:1454 : 
End of file while reading data: Input/output error
2015-11-25 02:26:38.953+0000: 3897: error : vboxInitialize:932 : 
internal error: nsIEventQueue object is null
2015-11-25 02:26:38.954+0000: 3893: error : virNetSocketReadWire:1454 : 
End of file while reading data: Input/output error


Any pointers would be greatly appreciated.

Thanks!

-Ken