Just installed FSUIPC and still get the error from installing GSX
That means you simply got a G3D.DLL error that FSUIPC can't catch but, that's not caused by GSX. It's likely a problem with your video driver, an FSX setting or tweak that shouldn't be applied.
You are mislead thinking it's caused by GSX, because it seems to go away if you remove it but, that doesn't mean GSX is the cause, it's just you don't have any other object/sceneries/airplanes that use/need some otherwise absolutely normal and standard graphic features that not so many addons use (but GSX does, like vertex shaders) that are not working correctly either because of a video driver problem or an FSX tweak that shouldn't be set on your system. So, GSX is not the cause, is the victim of this.
- 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 have the "Advanced Animation" option enabled in FSX Graphic Settings.
- Be sure you apply the HIGHMEMFIX tweak to the FSX.CFG, you can enabled it with the Addon Manager too.