If you get something like a blue-screen, the only possible explanation would be a video driver problem.
Fact that happens at KLAX, doesn't of course means KLAX is the problem (you surely must have suspected it, since you say it ran well on your old system), it's just that KLAX uses more video-card features, so it's more likely to expose video drivers issues, bugs, settings problem, compared to other sceneries that use simpler kind of graphics.
- First try to reset your video driver settings to default. Be sure you don't use "Transparency Antialiasing" (or "Adaptive Anti-aliasing" ).
- If that doesn't work, try to update your video driver too.
- If that doesn't work, try to reset your %APPDATA%\Microsoft\FSX\FSX.CFG file, to have FSX rebuild a new one with default settings
- Be sure you apply the HIGHMEMFIX tweak to the FSX.CFG, you can enabled it with the Addon Manager too, that's the only setting that really needs to be applied.
If it still not fixed, perhaps you applied some strange tweaks to your video driver that can't be reset by simply resetting the driver to default and/or reinstalling the driver. You might try a video driver cleaner utility, then a video driver reinstall after cleaning.