Mega-Global Fruit Corporation of Cupertino, USAnia, I am losing patience. "Update me!" say various iProducts so, rather than download 400 GB three times – once on each PC running iProducts – I select "Download Only". Then I can, and do, copy the stuff to a network drive and it will appear in the right place on the other boxes as is by legerdemain.
Clicky clicky install install and all goes swimmingly until iTunes. iTunes tells me it cannot access C:\Program File\iTunes, because privileges. It has a point, because I can't access it either, and I'm an Admin. I cancel the install, which takes ages, and check again. Nope, still can't access it. Do system restore. Oh, look! The security settings on C:\Program Files\iTunes are back to what they should be!
Try update again, one piece at a time, keeping a weather eye on the security settings. Shortly after beginning the iTunes update, the folder becomes inaccessible. Yes, FruitCo's update thing is FUBARing the security settings ON THE FOLDER IT'S TRYING TO INSTALL TO!
System restore. Uninstall iTunes. Update other FruitCo products. Install iTunes. Security settings remain untrammelled.
Perform updates on PC in Great Hall. It all works.
Stop it, FruitCo! Just fucking stop it and sort yourselves out!