Thank you for your post!
I'm not familiar with the issues you are encountering. I would think they are a result of Permission/OS Configuration as you mentioned. Could you provide a little more information:
-Do you download these installers on the Server machine itself or are they moved from somewhere else?
-What browser do you use to download?
-Can you attempt to run the installer from the Root of the C:/ and Run as Administrator
-If possible, use a Local Administrator User rather than a Domain User?
-You might try a different Domain User than the one you have been trying with.
-Is it possible to temporarily install something else on the machine? This will help determine if it's a problem with anything you attempt to install.