There's a Dynamic Campaign Generator campaign for Stalingrad at :
http://members.shaw.ca/dcgen/dcg_stalingrad.html

DCG is really cool because it continually generates new missions. You don't run out after a set number of missions.

Your errors in your mission may be occuring because of:

1. Missing aircraft in your AIRCRAFT folder

2. Some add-on infrastructure or scenery is missing
(make sure you have activated any scenery you installed).

3. An aircraft you installed may have the sound or panel aliased to an aircraft that is not in your AIRCRAFT folder.