This has been reported as being a driver issue. Please use AMD Support website and use the drop down menus to identify your graphic card. The path you need to choose is the following: Notebook Graphics > Radeon HD Series> Mobility Radeon HD 4xxx Series > Windows 7 (32 or 64bit).
To remove the driver, go to the Control Panel and select Programs. Identify ATI in the list and remove it then restart the computer and next time you enter the desktop, make sure to block the installation of the graphic card and proceed to install the downloaded package.