Never heard of this problem before.
Ban?
Probably someone reported you and Z8Games banned you unfairly...
Maybe you have put something incorrect in your crossfire folder.
Before I had the same issue. I sent them a support ticket and they unbanned me. But this happend a long time ago. I'm pretty sure Z8's ego has increased and they're relying too much on their "security system" to think everytime someone gets ban it's a legit ban always. They should realize it has flaws sometimes. -_-
if u log onto the website, i think it should give u the reason