It was brought to my attention that a member was having a problem posting to the 3rd Party Package Support Section.
I was able to with this account, and also reply to that post and make a new one, with a test account I had. Both of htese worked without any errors. The only thing that I can think of at this time is a 'COOKIE' issue. I would suggest that all members remove all cookies for the forum (via the "Delete cookies set by this board" link in the lower right corner of the Main Index page.
I can not verify that this will fix the problem, but is a good first step, as I can not duplicate the error myself. I will keep looking into this issue.