Petrsurf and Sumits81, hi, thanks for taking the time to respond. I have done what you [Petrsurf] suggested and it does stop the flickering but there is still a light blueish haze most of the time. I have checked every other possibility I can think of and it comes down to the icing. Remove this and it is OK but I notice it still defaults back to full icing effects next time. Frustrating on what is an otherwise superb aircraft. I think it will take a patch from PMDG to overcome it. If I keep completely shutting down the computer and re-starting, in time it will load unaffected, but it takes ages. It can't be your Track IT 5 or Ezdoc as I'm not running these at present. I do use REX but likewise I don't think its anything to do with these ad ons. I wonder if it may be to do with Orbx weather themes as I use most of Orbx's scenery and their weather themes, if not downloading real conditions. I'm not overclocked so Sumits81 suggestion of pulling this back a bit doesn't apply either. Probably boils down to FSX being an old system and also not made for HD either. I guess we just have to make the best of it and await a patch. Rob