Thank you... I have tried the workaround that g man offered but it does not work, you get the dreaded black screen every few seconds.....So as I stated before there should be a sticky saying do not use ATI cards with FSX if using Win 7/Vista, as Nick N said the best advice is to use Win XP 64bit...... there is a discussion on this at the Simforums website.....Thanks for all your help everyone.....Hamish...

There is another method other than using the Vsync that overrides. I have had this problem too, and couldn't even fly with the method that is similar to D3DOverrider but I tried a different way to enable VSync in ATT. Right Click the ATT icon go to 3D > Settings. In the 'General' tab select "Always On" for "Wait for Vertical Sync". In 'Additional' I set Catalyst A.I. to Low or High (Don't know if this could make a differenece if it is set to off) then in the 'Open GL' Tab I have selected "Triple Buffering". I use this in-case some avionics or add-on uses Open-GL to render. I read something about this a few years ago but I cannot remember where it was. I doubt OpenGL can work inside a DirectX app, but I just set it incase. Doesn't hurt :smile. Try locking your framerate as well. You may want to set it to your refresh rate (i.e. Monitor with 60Hz refresh rate, locked @ 60, 70Hz, loked @ 70), but first start of with lower #s and see if it works.Good Luck!

Just a small tip that will make things a little bit better... If you disable the brakes/stall/overspeed text warnings in fsx.cfg you can at least avoid some of the screen flashing. InfoBrakesEnable=False InfoParkingBrakesEnable=False InfoPauseEnable=False InfoSlewEnable=False InfoStallEnable=False InfoOverspeedEnable=False However stuff like the ATC menu and various addons will of course still give you the screen flashing. Personally I handle ATC and such stuff on a separate monitor so that's not an issue. Using these workarounds I get a bit less of the screen flashing but it's still too annoying to be acceptable though.

Thank you... So as I stated before there should be a sticky saying do not use ATI cards with FSX if using Win 7/Vista, as Nick N said the best advice is to use Win XP 64bit...... there is a discussion on this at the Simforums website.....

I agree on that one, I've tried the 5870 on XP and vsync worked as expected without problems in FSX. However Eyefinity does not work on XP and Eyefinity is kind of the reason I got the 5870 :(

Thanks for those tips.... will try that now.....I have Radar Contact so that may be a possibility.....Maybe ATI will release a new driver that addresses these issues, lets hope!!Hamish