tor won't start properly in virtual machine

I run Slackware64-14.2 on host. tor is 0.4.3.5 from SBo. tor starts and works fine

relevant log:

Code:[notice] Bootstrapped 0% (starting): Starting
[notice] Starting with guard context "default"
[notice] Bootstrapped 5% (conn): Connecting to a relay
[notice] Bootstrapped 10% (conn_done): Connected to a relay
[notice] Bootstrapped 14% (handshake): Handshaking with a relay
[notice] Bootstrapped 15% (handshake_done): Handshake with a relay done
[notice] Bootstrapped 75% (enough_dirinfo): Loaded enough directory info to build circuits
[notice] Bootstrapped 90% (ap_handshake_done): Handshake finished with a relay to build circuits
[notice] Bootstrapped 95% (circuit_create): Establishing a Tor circuit
[notice] Bootstrapped 100% (done): DoneI also have Slackware-14.2 in a VirtualBox VM that I'm using as sandbox for testing stuff. Same tor version. I won't claim the guest system is totally identical though.

For some reason tor fails to start on the guest system.

It gets stuck after

Code:[notice] Bootstrapped 0% (starting): Starting
[notice] Starting with guard context "default"What can I do to try debugging this?