HDMI dual view sync problems


TS Rookie
Hi all.
Help needed please.
I am running windows 7 x64, triple core amd, 4gig ddr3, and ati 5750 gfx,
I have been running a dual view setup without problems using hdmi to my onkyo amp and which is outputting 1080 to my 42"hitachi lcd screen .I tried drag a game onto the lcd screen and i got a no sync message come up the screen and a black screen .Now whenever i plug the hdmi cable in to the gfx card and reboot it displays the bios setup but as soon as it goes to windows it loses sync with the lcd and switches the main desktop screen off.
I have uninstalled, reinstalled various ati drivers at least three times and used driver sweeper to be sure it was cleaned up .
If i plug the hdmi from the pc straight to the lcd screen everything is fine ,i have tried different hdmi cables and used other hdmi ports on the reciever and as i say it works when not in windows.
thanks in advance