Have you raised the "Anti pop-up" slider in the Addon Manager ?
While this will surely improve smoothness, it will require way more memory so, if you are already close to exhaustion, because your settings are too high, or you are using a memory-hungry airplane, or you use too many AI, or a combination of all these things, on a 32 bit sim, you will likely end up your memory. An ntdll.dll error can (and it usually is) be a too few memory error.
As I've said, the more you are close to memory exhaustion, the more your memory is fragmented, the more it takes to close the sim. Of course, all of this is only relevant to the 32 bit simulators. Under P3D V4, memory problems no longer exists.
Some ways to reduce memory usage in FSX:
- Enabled DirectX 10
- Use the Steam version
- Reduce the Scenery Radius and the Autogen
- At KCLT, disable the 3d cars on parkings using the CTRL+F12 menu for KCLT.
- Set the Addon Manager Anti-popup to low values, like 1 or 2