Unfortunately, it's a common problem without a clear solution.
You can try these:
Reinstall the ATI driver. It's recommended to launch Windows in Safe Mode and uninstall everything ATI-related, including the DAO/MDAC component as well. You can use the ATI removal tool utility which can be downloaded from the ATI website.
Go to System Devices in My Computer > Properties > Hardware, and locate the option, PCI standard PCI-to-PCI bridge. This could under other names on your PC, so contact your PC vendor if you’re unsure. Right click, and select the “update driver” option. Manually search and install the PCI standard PCI-to-PCI bridge.
Right click on My Computer, Choose Properties, Choose the Hardware(Tab), Choose Device Manager (button), Click the [+] next to System devices, Right click on CPU to AGP Controller, Choose the Update Driver (button), Select Install from a list or specific location (Advanced), Choose Next (button), Select "Don't search. I will choose the driver to install.", Choose Next, Select PCI standard PCI-to-PCI bridge Hit Next, Hit Finish, Reboot.
