It was a bit difficult to figure it out, but during a couple of days I fixed the problem. I have a DELL laptop windows 7 system with AMD64 duo core and ATI videocard.
First of all you need to download driver sweeper ( just google it) and also the driver of your ati videocard. In my case I got my DELL driver update and that include catalyst also. If it is not included download catalyst, but a very early update.
OK. now uninstall all of Catalyst/ATI components and also the driver from your ati video card.
uninstall Catalyst/ATI components by going to control panel and then programs.
Uninstall ati videocard by going to control panel and device manager.
Now you install driver sweeper.
Restart your system in safe mode without network. A allround video driver is now installed.
Use driver sweeper and choose to clean AMD video driver.
Restart your system again to normal mode.
Now install catalyst and restart system.
Now it is working again