I get that sometimes too.
The easiest way to solve that problem is to add a few spaces after your sentance, and if that isn't enough add few empty lines with nothing but spaces.
It's probably a spam filter that's set to high. Think it checks what you posted in the past and if it sees certain word combinations it gets triggered.
Same here. I was told to CTRL+F5 and post again. To be safe, I now have a habit of copying what I'm about to post before I click anything. Not just GD, but many sites, especially if I wrote something fairly long. Posting errors annoy me, so at least if I've copied what I've written - I don't have to do it again :)