Here's more info on this.. I've donwloaded the .iso image from Technet site. Burned it at 8x and 12x speed. I've also, burned it slower the second time 'cause I suspected in that DVD burning speed.. So each time I've run a setup I was getting the same error during key validation. This is what I did: Rebooted my notebook, clicked install Vista, selected installation language, keyboard etc..After that I was asked to type the product key. When I entered product key I got an error: "windows installation has encountered an error and needs to be restarted". This was happening each time I tried to enter the key.. It seems that the problem was in Vista version detection, which is done when you enter the key.. @Spooky, laptop is IBM R52. If I can judge by these posts of yours guys, I can only guilt my laptop or my DVD, but I wouldn't say it's DVD since I've burned it twice on different speeds and on the different DVD burners. This issue most probably isn't a bug, but what about Active Directory Users and Computers MMC snap-in? It wasn't workin' on any previous version of Vista and apparently it isn't working with this final version too.. But there's a small guide on what needs to be done to fix this problem. I've posted it on my forum HERE I still haven't tried the MMC AD Users and Computers Snap-In on this final release since I've just installed it, so I'll try it tommorow and let you guys know how it works..