When I try install GSX Pro. I have always same error. Also I have 350GB free space in my C: Drive and I have 200 Mbit fibre broadband. I tried every solution on forum but nothing changed. GSX World can't install properly but GSX Pro files installs perfectly.
Try removing all ZIP files related to GSX world of jetways from here:
%APPDATA%\Virtuali\PackagesCache
clear your browser cache, and try again, so it will download them again.