After installing new Radeon GPU and drivers, Windows stuck at starting

Disable ATI Catalyst:

It is a device driver program for ATI Graphic Cards. Disabling it can solve this problem:

Click Start, point to All Programs | Accessories and select Run.
Type RegEdit and press ENTER.
Expand HKEY_CLASSES_ROOT -> Directory -> Background -> ShellEX -> ContextMenuHandlers.
Delete the key named ACE and then close the Registry Editor.

OK, I received my replacement card today. Still having the same problem. Apparently it's not an issue with the card itself.

Can anyone recommend my next step??

OK I've managed to get it working -- sort of. I tried installing a fresh copy of Windows 7 on my second hard drive, and then immediately installed the ATI drivers as soon as it was up and running. That worked -- the card is recognized. However, I'd really love to be able to get it working on my existing copy of Windows 7, which is on my SSD drive and which I've already configured. I really don't want to have to format my drive and go through the hassle of re-installing every program and hunting for license keys for everything.

To try and recreate the environment of a fresh installation, I've tried to disable the Intel 3000 display drivers. I've already uninstalled the ATI drivers completely. Now my device manager just shows the Standard VGA Graphics Adapter and the Video Controller. However, when I try booting into normal windows, it stalls at the Starting Windows screen (just like it did when trying to load the Radeon drivers). I can only access windows through safe mode now. Ugh.

Does anyone have an idea of how I can keep my existing installation of Windows but get this *#$! card working? I've tried the trick of uninstalling everything from ATI/AMD, including cleaning out the registry and appdata folders. That just didn't work.

No, I removed the card, booted into safe mode, disabled the radeon driver, rebooted into normal windows, and then deleted the drivers, as well as all appdata and other folders, registry entries, etc.

I gave up and just reformatted my SSD :P I've got the card working now. No idea what was installed previously that was preventing the drivers from working correctly. If some update or reinstallation causes problems I'll post about it here, in case others come across the same problem.

Hi, i just recived my Asus HD7850 today and had the same problem but i managed to deal with it... appearenty problem was in one app called iDisplay that extends destop to my android phone. I uninstaled it from safe mode and after restat win loaded normaly... Maybe you have some application that is interfearng with video drivers....

best luck.

my spec:
CPU: i5 2500k @ 4,4 under Mugen 2 rev.B
MBO: ASRock Z68 Extreme3 Gen3
RAM: Kingston DDR3 8GB 1600MHz HyperX
HDD: WDC WD6401AALS-00L3B2 (596 GB) + WDC WD10EARS-00Y5B1 (931 GB)
VGA: Sapphire HD 5770, 1GB GDDR5 128bit
PSU: Corsair VX450
Monitor: ACER V233HAbd @1080p
OS: Windows 7 Ultimate 64bit
Mouse: MX1000
Keyboard: Genius KB-G235
Headset: KOSS SB45

Had problem similar to OP while attempting to reinstall Windows 7. I could hear Windows 7 booting up but the display was stuck to the background. Turns out that displays were set incorrectly and my monitor was looking at the right (or left, not sure) of where the action was. I found this out by disconnecting the second DisplayPort from the card and then the display looked correct.
Lesson learned: When display looks stuck, make sure to move mouse way over to the right or to the left. If the mouse goes by, the displays might be set incorrectly.
In my case, the second DisplayPort is connected to the TV which wasn't on when I was reinstalling Windows 7. It was a fluke that I decided to try removing its connector.

Note that I do realize that the above may not explain the problem and the fix for the OP. I am posting in case this helps someone avoid the frustration I had of looking at a "stuck" display for way too many times!