>>>>If you look at the attached image you will see that sometimes a DLL can be blocked by Windows, when it "comes from another computer.". But how do I block a DLL on-demand? My DLL is not blocked but I want to block it so that I can run a test.
>>>>
>>>>TIA
>>>
>>>https://msdn.microsoft.com/en-us/library/dn392609.aspx
>>>https://blogs.technet.microsoft.com/askcore/2013/03/24/alternate-data-streams-in-ntfs/
>>>http://woshub.com/how-windows-determines-that-the-file-has-been-downloaded-from-the-internet/
>>
>>Thank you.
>
>You're quite welcome. Ran into this issue a few years back. Files that had been downloaded form the Internet were being blocked. This was especially problematic when we had delivered an installation file or program patch through the Internet (e.g. via Web download, FTP transfer or attachment through E-mail). In some cases the security had locked things down to the point where such files could not be accessed. In some cases, the security was configured to NOT give the warning dialog and automatically fail the access -- in such cases we'd get the rather puzzling situation where we'd get "file not found" errors although the file is indeed listed in Explorer.
>
>You'll also have to remember that his relies on a feature of NTFS, meaning it's probably not going to work when a NAS, external harddisk or thumbdrive is involved (since these may not always be using NTFS).

Let me clarify. My goal was/is the opposite. I am trying to simulate the situation (on my PC) where a file (specifically a DLL) would be blocked; as if it were blocked because the file was downloaded from the internet. So far, I was not able to "block" the .DLL. I remember when I downloaded it first from the web it was blocked, I unblocked it. But now I want to go through the process again. Perhaps this (blocking the file at will) is not possible.