I experienced shaking screen on Welcome page and Shut down page of Windows 7 Pro 64bit since november 2010.
I got an RMA from Powercolor for my HD 5770 video card because it was doing the same shaking problem on both high end PC (one AMD X3 and one Intel Core 2 Duo).
PowerColor returns me a brand new video card with an updated BIOS but guess what, same problem with Catalyst 10.12.
Before asking for an other RMA, I did a clean uninstall of Catalyst 10.12 and I tried new Catalyst 11.2.
The shaking screen problem is now solved for me, I'm now happy with a brand new video card. It was definitely a software problem and Powercolor had no idea about it.
I'm a little worried about AMD ATi driver developper's skills (do they actually test new drivers on each operating system before releasing them ?)
but that's not new (I will definitively go with Nvidia card next time !).