The drivers are just buggy. Catalyst 5.6 behaves correctly. Anything newer, if the EDID info goes away, the DVI port is shutdown and the card does not reenable when display comes back on line.
Either change the resultion using hotkey to change res (which I think you are saying doesn't work anymore), backout drivers to 5.6, or purchase DVI detective. On the side, please lodge your complaint with ATI until they fix the problem.
Either change the resultion using hotkey to change res (which I think you are saying doesn't work anymore), backout drivers to 5.6, or purchase DVI detective. On the side, please lodge your complaint with ATI until they fix the problem.