Duplicate post error after upgrading to 3.6.5

[wtricks]

Hello

Yesterday I mustered all my courage and made the jump from 3.5.5 to 3.6.5 .. all went almost OK. I lost some of the theme settings and images, but I had all backed up. And in few hours I had them up and also worked more on the codes to implement some other ideas.

So far it's OK. Except for a weird error I get when posting:

This post is a duplicate of a post that you have posted in the last five minutes. You will be redirected to that thread.

That happens to all my posts and I didn't find a way to solve this. I used the maintenance tools and recount indexes and posts and others. Maybe I forgot something?

Here is what a member reports:

Error with Quick Reply: When I press 'Post Quick Reply' it posts and then takes me to the newreply.php where it says I need to wait 7 seconds (but It's already actually posted the message - like it's doing it twice

What should I do to solve this?

Thank you in advance.