I have seen a few issues with ATI applications and .NET. Its not the drivers that are written in .NET, its the other application like the control panel for ATI.
I have made a registry fix that has worked for me every time. This registry file will remove all instances of .NET from your registry.
Step 1. Uninstall all ATI software and drivers
Step 2. Uninstall All .Net installations
Step 3. Download and run this registry file and select yes when prompted
http://smstech.dnsalias.com/remove_dot_net/REMOVE%20DOTNET.reg
Step 4. Restart computer
Step 5. Reinstall all .Net versions
Step 6. Reinstall ATI software and drivers
Hopefully this helps you fix your ploblem. Good luck!