Acer Aspire 5740g HDMI no picture, no sound

Hello !

I'm having this issue for a long time and I totally cannot find the answer to my problem nowhere. I have an Acer Aspire 5740g with an ATI card : HD5650 1GB running on windows 7 64. When I connect my laptop to my TV via HDMI , it detects the TV but I CANT display picture on the TV. I tried the newest display drivers 12.8 , some old ones as well. I checked out two HDMI cables and two TV sets: Toshiba and Sony , both full hd .

When I connect the TV , my laptop detects it normally, and it is shown in the "screen resolution" window. When I click to switch the picture to TV , the laptop screen goes black but nothing happens on the TV screen, and it goes back to the laptop screen because I dont accept the changes. There is no sound as well even though the icon in the volume setting window is changed to TV speakers.

I went to a "computer specialist " who said he fixed it by installing new drivers from the manufacturer. I paid the guy but it still doesn't work for me ! BTW the drivers from the ACER website are totally out of date and it appears there is no support on the website whatsoever.

I apologize for my english and in case someone already posted such a problem. I hope someone can really help me .

PS: I will never buy ATI products ever again. I've been having problems with ATI since forever. My brother has NVIDIA and HDMI works like a charm.

Thanks in advance.

B.K.