Mark, I haven't been able to replicate this issue, or find any other reports of it. The most common reason for the message not posting would be browser related. You may want to check for a browser update, or try an alternative.
If you can provide the browser name and version you are using, I can look into this further.
Also, any details on where exactly you attempted to post, and any errors you may have seen.
Hopefully we can get you back to posting quickly, and into a keeper league.