hmmmm you got 3 choices:

      1.) Don't start a new campaign
      2.) Do the cure all-reinstall
      3.) My personal favorite - TANTRUM!!!!

Jeff

Have you been messing with the stock aircraft xdp files or something?
Think this can happen if the Sim can't find certain types of aircraft in it's folders like level_bomber.
Just a try, locate the uisel.xml located in C:documents and settings\yourusername\application data\microsoft\combat flight simulator 3.0 and delete it, it will be newly created when you run the game next time.
You'll have to rtweak any users settings you have applied like custom keyboard commands and the like.

Mathias & Jeff, The campaign problem was due to a mistake at the install of the updates. I put 3.1a in first. I reinstalled correctly and everything is working fine. 

overland48

adrick
     All I can tell you is to try a reinstall again. Install the game then patch  with 3.1 and then 3.1a. When I followed this procedure all went well. Make sure you meet all game reqirements for your system.

overland48