hmm ... what you can do, it's ask on wmvare forum, is there abny possibility to change the static ip adress (the one you get with running virtual os) to the dynamic ip adress.
you can try to change adress under the virtual os. in controll panell -> network connection
right click on connection -> tcp/ip -> properites and set up a ip adress. after that reboot v os and try it now.
and last but not the last thing. check on your's router producer (on on
http://portforward.com/ ) is there any possibility to change behavior of this router. to get 1 ip adress at a time (not sure this will work's)