You're not banned from anything.
Please email me a screen shot of the error message. What I am willing to bet you are seeing is the "Forbidden" message, which is a result of our firewall blocking postings which contain certain special characters or sequences of characters.
In 2012 we were the victims of an SQL injection attack. All systems which are backended by an SQL database and take user input are vulnerable to this type of attack. I didn't feel that the forum software was adequately protecting us, so I hired a security consultant to put another alligator moat around the site. This has worked extremely well, but it does have the consequence of occasionally blocking legitimate posts.
My suggestion is to minimize the use of special characters in the body of the post, and don't use any in the thread title. If you eliminate those characters and still can't post, I will check the logs to see exactly what firewall rule was violated and try to refine the ruleset to allow the post.
My apologies, and I'm sorry that rather think it was a technical problem, that you assumed we'd taken some adverse action against you.