I just wanted to give some of you a headsup if you can't post or reply. Tech support will most likely tell you to create a new account which is a bummer because you wanted to use a certain name for the forums.
So here is most likely everything you did.
1. Tried different browsers and computers and well as cleared cache and all that stuff.
2. Created a new account and learned it posted and replied fine.
3. Contacted support and they really couldn't help
Here is how I fixed the issues and verified what the problem was at least in my case. I did all of the stuff above.. I even logged into 3 seperate computers with different browsers and still could not post with this account. I created a new account and it posted fine.
Here was the fix and I am not sure why. I changed email addresses on this account under my profile.
I have no idea why the associated email with this account has a problem but I verified. I changed this accounts email to another. Logged out and logged back in and it worked fine. I then went to the scratch account that I used to test posting with. I changed it's email address the the email that was formerly attached to this account. Now all of a sudden the account that was working, stopped working. I could not post or reply with that account. So I changed it's email to a different email address. All of a sudden the spare account started working. I logged in with a 3rd working, test account. It could post and reply fine. I changed it's email to the email that was associated with my original account. Poof.. now that account cannot post and reply.
So for some reason the unable to post or reply problem seemed to be following an email account. I have notified support and they did send it up the ladder as they said they had not seen the issue before
The good news is. You do not have to lose or not be able to use your original forum name that you wanted if you are having this problem. Try this out and see if it worked for you. I registered this account in 2008 and have NEVER been able to post with it until now. It was just a simple email change that fixed it.
Hope this information can help some of you. It worked for me.