Having written a post and succesfully uploaded a screenshot I hit POST MESSAGE and get taken back to the log-in screen (I am already logged in). Am I missing something??

This can happen when using security software blocking cookies, like for example zonealarm.Or by using a high security level in IE, and not allowing the particular site to override that security level.In eighter case you have to access the advanced options, and give the necessary permissions to the site you want to work (in this case avsim.net or forums.avsim.net).Hope this helps