I always "preview" before posting, and got a mssg saying -
The following error or errors occurred while posting this message:
The message body was left empty.
Even though I had attached the screenshot, I typed a single word, did it again, and no screenshot showed, even though I attached it. I then posted. I was taken to a blank white screen with a forum address, no other error mssg. When I looked at the address in my browser, I was taken to a "reply" screen, just as if you were getting ready to enter a response or type a new mssg.
Since I dragged my taskbar to the side of my screen, I was able to reach the "OK" button to save my changes in Firewall -Settings- System Rules. I'll keep trying to post the screenshot. The system rules window needs a scroll bar on it.