Without knowing exactly what is happening to you, its hard to just guess. What exactly happens? What msgs do you get?
If its a msg telling you to enable identd, some networks have had so many probs from users from certain providers that they insist all users from those providers (the ppl you pay for your internet service) enable identd.
Banning may not be aimed at you specifically, but on all ppl within a certain ip range and you are getting caught in it.