thread closes since I was able to correct the problem.
What I learnt:
1> try posting BZflag related queries on http://bzbb.bzflag.org
2> the channel 'bzflag' in irc.freenode.net is an excellent place for quick troubleshooting.
I logged on to the irc channel mentioned above and got help from a user "Cosmos".
The problem was "wrong display settings" for the game. Once I changed the resolution, the problem got solved.
changing the resolution can be performed by getting into the options and then searching for the display options and then setting the resolution correctly to the current resolution. Since mine had a higher resolution set (I guess that by default it gets set to the highest -?? ) I changed it to the resolution that I currently was using and all problems vanished.
Also to try out if this was a resolution problem or not, ran the game from the terminal through:
bzflag -window -geometry 640x48
this worked fine meaning that it was a resolution issue and not a firewall issue.
thanks 'Cosmos' and BandC.