Ok i got it working, after trying for about 1-2 days , i tried every single fix in the internet.
Try this as your last resort, and IT SHOULD work.
first of all, close any programs you have running, make sure on the bottom right of your task bar that u have all background programs OFF, make sure your skype isint running or msn etc.
next were ganna add firewall rules to the diablo 3 installer.exe , type firewall into START, and in the right side or left its going to say , Inbound and Outbound rules, make sure you add the diablo 3 installer US.exe as a program on both of them and enable it it connect to everything.
once that is done, here comes the more technical part.
goto your C: drive > program data ( you might have to set your organize folders to view hidden files) > battle.net
delete your battle.net folder , and then goto C:drive > program data > blizzard entertainment > delete the CACHE folder , if you dont see it, it might be within the battle.net folder.
OK next we have to enable secondary logon.. THIS IS recommended.. if you want to ever play diablo 3, todo this goto start > type services into the run bar, a little gear pops up called services, click it and when it opens look for "Secondary Logon" it should be in alphabeticle order on the list, right click secondary logon and goto properties, once in the properties look near the middle of the box you will see where it says "Start up type " click that and make it "Automatic"
Next , make sure your Diablo 3 Installer US.exe is set to run as administrator.
Final Step, Goto START > in the run bar type msconfig and press enter, when the system configuration box pops up click the top general tab, click selective start up .. UNCHECK everything under it except "use original configuration" select selective start up again and check on "load system services", RESTART your computer, once the restart is complete run your diablo 3 installer.. it will take about 5-10 minutes, dont get annoyed and think it wont work.. thats kinda how i felt, but depending on your computers speed it will work, just give it abit of time.. now im happily installing and enjoying an awesome game :).
I hope i helped.
This should fix your problems, i made afew typo's but its because im typing quick.
Edited by Trait on 5/15/2012 11:44 AM PDT