Hey guys. As long as you're going to be charging people for this, why not put a little effort into making sure it'll actually work?
I've paid for and downloaded the "2.5" installer for the Pro version from the site just today and am having the exact same problem retrieving from isscript.msi as others have reported.
The problem, though, seems to be that this
www.installengine.com system isn't in the DNS! I've tried several different (known working) DNS'es, and none of them know about this system. Wanna give us a helping hand and throw us the IP address(es) for this name??