This looks like the issue ATI Radeon HD 3000 and 4000 series cards can have.

If you have one of these cards, this workaround ought to help though it's a bit of a hassle.

1) Uninstall the currently installed video drivers.
Use a driver cleaner app if necessary
2) Install 2011 drivers (11.5 is what was tested in-house).
3) Ensure the “Disable Catalyst A.I.” is unchecked.
4) Test out Diablo III to make sure no graphical issues are seen.
If not, back track the drivers further.
5) Install the latest 12.3 drivers once again. (not 12.4)
6)  Try the game again wth the newly installed drivers, Catalyst A.I should now work too.

____________________________________________________________________
Support Information Administrator