CW3SF, 
  
Did you find a solution?  I started having the same problem right after installing the 1.47 patch.  Before then, OFF/HITR was working fine for me except for a failure to populate airfield message that didn't affect the game at all.  Then after the patch, I couldn't fly two missions in a row.  Instead, after clicking on "Go to Briefing" for the second mission, I would get the run time error and crash.  I would restart OFF, fly a mission with no problem, and then the problem started on the second mission.  Now for the first time, I've had a mission  fail to load, so my plane is sitting on the runway, but I have not control over it.  I exit the mission, but the campaign fails to advance.  I start the mission again, and I get a run time error again.  I exit OFF, restart, and the process begins again (fails to load, plane on runway, exit, restart mission, runtime error, crash, repeat).  Because my download of HITR was very recent, I'm wondering if I needed the 1.47 patch or did I mess things up by downloading it.  Thoughts?