Well, 10 NM out is consistent with the scenery loading area but, that doesn't mean the scenery it's the cause either. Maybe you simply have too few memory (or video memory) left, and as soon the scenery was loaded, it simply wasn't enough.
If the scenery had a problem, everyone should noticed it just the same. I've just checked it again now, both by enabling the ShowMissingTextureAlert=1 feature in FSX that would alert if there's a missing texture somewhere AND by enabling the FSUIPC log, that tells when FSUIPC is trying to fix a G3D.DLL.
There were no missing texture alerts, and no message from FSUIPC that even a single G3D.DLL crash might have happened and it tried to fix it, nothing at all, and I've went back and forth many times in and out the 10 NM threshold, forcing many scenery loads/unloads and stressing it on purpose just to make it intentionally crash, but nothing and no warning messages of any kind, from FSX or FSUIPC either.
You might use the free Process Explorer utility, and check the memory allocation for FSX.EXE when you load PHNL, that would give you an idea what's happening.