You will see this if you try to make a couple posts very close together in rapid succession.

The flood control keeps someone from making a bunch of spamming posts in rapid fashion or from having one of the spam bots trolling the web posting a bunch of garbage and essentially running all the legit posts off the bottom of the page. The verification number when you log in is also to help control automated responders or bots from posting a bunch of junk too. 

A minute or so between posts should allow you to post mutiple replies.

There is nothing wrong with your computer or the site software it's just a way to keep the spamming under control.