It's no use checking the filesize.
Our files are all digitally signed so, if they were corrupted (even a single byte changed from what it's supposed to be), the digital signature would be invalid and you'll surely noticed it, because FSX will warn you about the publisher being unknown. And, you can always check the Digital Signature itself on the file properties.
And yes, it's normal they will be of different sizes, even if only the version number changed.
By the way with any bglmanx.dll (corrupted or not?) I have no crash when starting at Houston, with or without shadows.
So you are crashing ONLY at KMEM now, and only if you play with the aircraft shadows settings ? I'm starting to think that the software itself doesn't have anything to do with this, and it's simply an issues of FSX not being able to handle shadows at KMEM for some reason, something that must have been fixed in P3D (which has an entirely different way of making shadows) and in FSX:SE, because it uses less memory in general. Perhaps they are just taking too much RAM...
We used to do sceneries with realtime shadows completely disabled but, in KMEM, some objects like the animated crews on the parking really required them (a static shadow on an animated guy doesn't look very good). What is puzzling me, is that we never display more than 2-3 of them at time, so they shouldn't take much memory.