I have noticed that sometimes I get a green progress bar when either starting a thread or replying to one, and then the post goes up ok.

 

Other times, like today, there is no progress bar, and after waiting a few minutes I get a 'service not available' message, and it appears to have failed to post.

 

In actuality the post did go up but if you hit the back button to go to that forum you don't see it, so one assumes its not there and some post again.

 

If you actually leave that forum and come back, then it shows up, and I am sure those posting duplicates arent aware of this, so just thought I would pass this along

 

The safest course of action when you get the "service not available" message is to hit the F5 key to force a reload of the last used URL. This will -when successful- show your posted message.