hey, I found that out, the problem was with gdm.conf:
Note: gdm seems to have an annoying setting that causes x11vnc (and any other X clients) to be killed after the user logs in. Setting KillInitClients=false in the [daemon] section of /etc/X11/gdm/gdm.conf avoids this. Otherwise, just restart x11vnc and then reconnect your viewer.


Cheers,
-nik

Excellent!