I too got this game today and guess what ( shock horror ) Same Problem
here was my fix for this Problem
the same fix I used for star wars
My PC is Windows XP sp3 — My laptop is Windows 7
This game will not install clean onto my PC but will not miss a beat installing onto my Laptop So install it onto my laptop I did then copied all files over to my PC and run game..
Now don’t this seem strange I run same McAfee Virus software on both systems and almost the same software in total.
Yet I downloaded and installed Diablo III onto my Windows XP system no probs.
So you can draw your own conclusions to this I HAVE….