Active pause, or actual game pause? The difference is that in the normal game pause there's a pause icon at the top right of the screen and nothing moves or operates in the game. In active pause there's an ACTIVE PAUSE label and your aircraft gets frozen in place, but all the avionics still works, other AI units still move/fly around, etc.
It sounds like your pause button isn't mapped - maybe the configuration was lost during your patch process? I would recommend double-checking the pause button mapping in the game controls and set it to something you know works.
[edit - Looks like WC found a good link for ya!]
Last edited by EinsteinEP; 08/24/11 08:24 PM.