Hi Team,I had to re-install the 737NG, which I first did with the removal tool. All went well with no problems, I am running FSUIPC 3.48. Now when I take off, the planes climbs perfectly and handles just the same. All autopilot functions work as they should. Then when I reach altitude for example 34000 feet, the plane levels off and then begans a slow climb to 45000 feet. This has never happen with over 1000 hours in the NG. If I click on level change the plane will make a slow descent but does not come back down to 34000 feet. Vertical speed is almost inaffective.I check this behavior with both ActiveSky 4.5 and FS Weather over different routes with the same results. I am running Windows XP SP and FS 9.1, do have any clue on what could cause this problem?ThanksBob Johnson

Well since I got so many replies (grin), I found out why the NG was not holding its altitude. Try corrupted files!!!!!!!!!!!!!!!!When I re-installed the NG I started with the Remover Tool. Then installed the base V1, forget to use the Remover tool. Then went to V2. What would be very helpful for the PMDG team to list the files needed to install from scratch, in the correct order. This would be a good FAQ IMO.Be careful how you reinstall.Bob