This has been bugging me for days.Pre SP1 FSX ran OK on my system - reasonable framerates with some autogen, AI traffic, road vehicles etc.Then I upgraded to SP1 and got much improved framerates, but absolutely zero AI traffic regardless of where the traffic sliders were set.The upgrade process was as follows. Since I needed to replace the hardrive I installed XP (with SP2) onto the new drive, made sure DirectX was v9c and installed RTM FSX. Then I immediately installed FSX SP1 (ie did not run FSX before hand). Loaded up as normal, went through the normal configuration and ran the sim. Everything else seems to run perfectly, smooth performance, autogen. I have tried most of the aircraft, all run OK, and tweaking all the other display settings has the expected effect.I have checked all files I can, traffic bgls' seem OK, config file records the AI traffic slider settings.I've run out of ideas - any suggestions ? I guess I've missed something obvious.Thanks in advance for any help.isaac

Did you put your AI aircraft in a folder different than SimObjectsAirplanes ?The new(old) path needs to be added to most people's fsx.cfg after the SP1 install.

Thanks for the tip, I'll check this out and report back later. For clarity this problem is with the AI traffic included with FSX - I have no addons installed so far.

Update:System is E6600 core duo, Abit m/board, 2Gig Ram, 8800GTS 320Mb. Typical post SP1 frame rates of 25-30 @ 1600x1200 and mid range slider settings.Removed FSX Install. Re-installed FSX RTM (no addons) and ran it. Got a few AI Aircraft with sliders maxed (!), no ground traffic regardless of slider position.Upgraded to SP1. Still no ground traffic and a tiny amount of AI Aircraft scattered about the area - no arcraft at local airport.Its almost as though there is some global setting that disables AI. I have tried setting the target framerate low and high, and have tried various slider settings.Searching on google suggests a few cases are appearing of this effect.Am now going through fsx.cfg file to try different values here.Will report back with more info. In the mean time if anyone has any ideas please let me know.