The two minutes between posts warning has been in place since the forum's inception. However, it can sometimes pop up if someone submits a post but gets the error that SMF was unable to connect to the database:
Connection Problems
Sorry, SMF was unable to connect to the database. This may be caused by the server being busy. Please try again later.
before the post actually goes through. Even though the post didn't go through, the system thinks that it did because the way SMF has written things is that the post submission is applied to what's called a member's session before the unable to connect error comes up (apparently it has to be written in that order :- ). But if this is happening without you ever seeing the unable to connect error, I have no idea why you're getting the two minute warning. I've never seen it except under the circumstances I just described. And the two posts that I made soon after yours went through as normal. And unfortunately there's absolutely nothing we can do about database connection problems because that's a server issue...
I know it gets repetitive to blame everything on Internet Explorer - but, sadly, that browser is so screwed up that nothing that happens to anyone who uses it ever surprises me.