Game/client won't launch

I downloaded the Diablo 3 beta client downloaded from the site...it would get to about 20% then an error message would pop up "Unknown error has occurred, please restart. If problem persists please contact customer service." Called customer service, they couldn't figure it out so they asked for my computer info. After providing it to them they suggested I update my drivers in my graphics card, so I did. With no luck I then copied the program files for d3 beta off my fiance's computer and it worked flawlessly, one time. Now when I try to launch the program thru the c drive, program files folder...nothing happens...I try to launch the download client...nothing happens. And if I go to control panel it doesn't even show that it is installed? I was able to play once after transferring the program files from another computer, but now I am back to square one. I feel like I have tried everything. (Fully REMOVED all anti virus/firewalls, used new admin vista user profile, updated drivers) Any ideas? :(

I was able to install Diablo 3 successfully once. I played through four times so far, and really enjoyed it. Except every time I tried to start the game, it would get stuck before the launcher, except when it would load the launcher, but lock up and "not respond" when it hit play. It took five to ten tries to get it to work, until it started Error Code 3ing nonstop. Nothing I tried worked, so I tried to reinstall.. And now I get the same problem as above, though it takes five or six tries to even get to the installer.

http://img249.imageshack.us/img249/4192/reinstallproblems.png

Sigh.