The graphics card is probably not seated correctly.
I would advise starting from scratch by just downloading the ATi driver only from the website:
and then the ATi Tray Tools software from:
which is a fraction of the size of the Catalyst ATi equivalent, yet has similar capabilities.
After uninstalling the current drivers, run this freeware:
to get rid of all the previous ATi entries.
Then install the new driver and ATi Tray Tools.
It works well for my Radeon 9550.