Edit: Must have been from leaving MSI afterburner on during install....ran it again with it off and no more window on boot. Thanks Tyraa your post on the other thread solved it for me

Sweet. I only saw a brief DOS window pop-up on my boot this morning, which is apparently normal with this driver set. A bit of Googling shows that this is the new OpenCL / AMD media library encoder starting up. It should only linger / do that "finalizing installation" bit on your first boot after you install the drivers, after that it's just a brief flash when it starts at boot. If it's lingering on subsequent boots for whatever reason, something done been broke.

Also, a word of potential caution for Crossfire users looking to upgrade their drivers: a number of people have reported that 12.3 forces one of their two cards to stick in 3D mode, even when just on the desktop (so when both cards should be downclocked and idling)--which causes a jump in idle temperatures of 10 degrees+.
This isn't universal...some people with Crossfire or even Tri-fire (

) are saying their cards are still downclocking like they should. But it's something to keep in mind. If you see this happening on your system after installing 12.3, I do recommend rolling back to 12.1 or whatever older driver set has worked best for you. "Idling" at 3D clock speeds is not good for your GPU.