did you enable the sweetfx addon? if so disable it (with ac fully closed) and try again.
if it still doesnt work be sure that dxgi.dll has been deleted from the root of your ac folder. see the sweetfx troubleshooting section of the mod description for more info. and use the discussion thread if you are still stuck
Awesome mod! Really loving the filters. The Photomode made my computer lag a little bit, but that's probably because of the processes that I had running at the time.
if it still doesnt work be sure that dxgi.dll has been deleted from the root of your ac folder. see the sweetfx troubleshooting section of the mod description for more info. and use the discussion thread if you are still stuck