There have been a few solutions posted around the forum. A quick search pulled up this forum, which might help:
Keep me posted.
I've been really frustrated trying to connect my MacBook Pro to my Samsung 40" HDTV (LN40A550). My computer recognizes that it is connected to the TV (i am using a DVI to HDMI cable), but the Samsung TV is NOT recognizing it, no matter what I do. I've tried every resolution, I've tried "rebooting" the TV a million times. I've tried refreshing the source a million times. No matter what it won't detect it. It is fine detecting other things like USB drives, my HDTV cable box, etc... but not my MacBook Pro... Has anyone else run into this problem and/or a solution to this?