The "Captca" problem has been going on for about 2 years now. There have been multiple posts about this, why is happening and what folks are doing to work around it.
It seems there are multiple reasons why it's coming up, "I am not a robot" is a familiar theme on these forums and many have offered suggestions.
The latest one I found that causes it to come up is the use of the right and left parentheses ) ( ... I reversed them, because if they are the other way, the "I am not a robot" will come up every time. So, when I get that, I hit the browser back button and remove any special characters. I started using dashes and comma's instead the parentheses.
Another reason it comes up is the length of your post. I have found long posts will make it happen too. I'm long winded and get completely carried away with my posts, so I hit the "I am not a robot" quite often.
Sometimes, if you quote another poster it happens too. You've go to go back and edit the quote sometimes.
This site is very fickle. But if you hit your back button and play around with our original edit, you can usually find the cause.
Another thing, there are other portals to these forums. Camping World, Trailer Life, etc. If you get the "I am not a robot", you can hit your back button and then copy your text. Then go to one of the other portals, log in, find the thread and "paste" your original remarks without have to retype everything all over again. Sometimes a different portal to these forums will work better. Here again, this is trial and error. I found the consistency to be special characters in the text.
Good luck, and hope this one posts because I included the parentheses.