FS9 crashes on loading Canadian airports...

Something is screwed up in my scenery or textures or whatever. Have been using this program for years, and have over a month and a half on my new system (imac). All was fine until a few days ago, it crashed if I loaded a day flight. (At CYXY). Night was ok, but any daytime load would crash to desktop.Turns out this behaviour has been reported with fall textures and Ultimate Terrain Canada (which I have). Went to a us airport - sim was normal.Tried uninstalling UT - didn't work. Renamed my FS9 folder, re-installed from CDS (forgot to formaill uninstall first, but don't think it makes a difference), just to ensure that the windows registry was ok. Took the new virgin install - all appeared normal. Installed Ultimate Terrain 1.2 from a new download from flight1 - got the same behaivour. DEFINITELY related to Ultimate Terrain.Read on their forums that it may be linked to seasons - switched from fall to summer - and the sim loaded fine.AHA thinks me - that is it. Just replace the old fs9 folder (with years of downloads in it) and simply change seasons to step around this problem.Nope - back to the same behaviour. Uninstall and reinstall UT and now it craps out if I load day or night at CYXY - it gets to the 77% loading weather on the progress bar, hangs then pops up the report to microsoft dialog. (different than the original crash which was straight to desktop.Tried removing my scenery.cfg file and forcing it to build one fresh - no joy.So, I have FSGenesis terrain installed, don't see if that has any connection, but I am at aloss as to how to get my sim working again!Suggestions?