Temporary IP Block?
 

I was hopping between my two p99 accounts. Guess I /exited one and logged into my other.

How long is the temp block usually?

30seconds - 3 or 4 minutes. Depends on if you have agro. If something is beating you to death usually takes until you die.

It was a short release. I got that message, then tried again a minute later and it let me on.

It lasts as long as your toon is in game.