Hi there,
recently a customer of ours has problems loading an arx for AutoCAD 2018. Unfortunately not on all computers - one of them loads the arx successfully. It makes no difference whether the file ought to be loaded from a network share or locally.
I had the opportunity to save sessions via Process Monitor when it succeeded and also on one of the machines that says, that it is an invalid arx. The only process touching the arx in both cases was acad.exe. No virus scanner, nothing else. The general pattern of operations seems to be CreateFile - CreateFileMapping - ReadFile with some CloseFile intersparsed.
I attached the logfiles, filtered on the path with the arx, just in case anyone cares to look inside

I also used the tool "DependenciesGui.exe" from
https://github.com/lucasg/Dependencies. After adding the AutoCAD bin path to the search folders the only file marked was "C:\Windows\system32\OLEAUT32.dll" and I think "C:\Windows\system32\mfc140u.dll", both of which are also highlighted on my machine which successfully loads the arx. Maybe one thing of interest is that the arx includes another dll and if this one is not included (during compilation), then the arx also gets loaded on those machines that otherwise say it is an invalid arx.
I'm totally lost and hope
anyone has a hint what else to do to find a solution.
Thanks in advance, Bernd