I have problems with fatal errors as well. Once I have installed the PMDG, Microsoft flight simulator didn't t start any more.This is seriously getting on my nerves... I've tried almost everything. Renaming the logbook and reinstalling the Accelration pack. The flight simulator then worked well again but when I reinstalled the PMDG, the Flight simulator wouldn't run again. I've also deleted and replaced the aircraft.cfg files and the livery manager isn't working as well. I have Windows 7 and believe that I don't have isntalled SP1. Might that be the problem? If that's the case could you please tell me where I can download the SP? Because I haven't found any good source. Please help me... It's really sad to see that a product I've spent 69,99 on is causing so many problems. Thanks Matthias