You can try adding yourself to the 'boinc' group, so the (local)user can connect to the boinc-client.
sudo adduser <yourusername> boinc
Then try restarting the VM and see if it(BM) works for you. It did for me, as now when I start up the VM and invoke BM it comes up with out a problem. Where it never connected before, but I was able to the two times I tried after adding my VM Ubuntu user to the boinc group.