[AS2] Question about movement

[RockHopper]

Hi, I need some help with something that's probably really simple.

I have a small character that you control with the arrow keys and you have to move him over to portals that teleport you across the stage. What I need to do is have the character stop moving after you go through a portal so that you have to lift up the arrow key and press it again before you can start moving again. Could somebody help me with this? Thanks in advance.

[RockHopper]

If you didn't see my other thread I have a game where you control a small character and move him into portals. simple I know. But what I need to know is how to implement point collision detection on the character and all of the portals. Thanks in advance!
heres a link if you wanted to see it:
http://rockhoppergames.com/play.php