Okay finally, after some hair pulling, it works. Lets hope it stays so.
Running windows 7x64, ATI 6950
So i have a dell u2711 and the vizio 3d tv attached to my pc. The dell via DP, and of course the TV via hdmi.
When i restarted the PC the other night, i noticed that the TV was getting a 1080p signal right until windows came up with the login screen, so confirming that it def was a windows issue.
Disconnecting the Dell, set TV primary, changed the refresh rate, rebooted nothing.
Uninstalled the ati drivers, rebooted, nothing.
Ran driver-fusion ( the upgrade for drive sweeper) it found a crap load of files, deleted all, ran MSI cleaner util and made sure nothing ati was left on my system.
rebooted, boom, 1080p, 3d button working merrily. Windows sluggish as hell tho, cause its using some vga save driver. Reinstalled the newest manufacture drivers (not the news ati ones(, restarted and it still worked! connected back the dell, switched it to main, hit that 3D button and it came up
TL, DR - In summary, make sure and absolutely clean all old drivers off your system and bring it back from scratch. it may be necessary for an newer driver to be the culprit. Not feelig to experiment with upgrading drivers at the moment.