HDTV going blank every couple seconds w/ PC?

I just hooked my pc up to my HDTV and I seem to be having some problems. About every 5 to 6 seconds the screen goes blank and my TV displays No Video Signal or Unsupported Video Format.

I have a 9800 GTX with a DVI to HDMI connection. When the screen isn't blank everything appears to be fine. I have set the resolution to 1920 x 1080 and everything checks out but for some reason I lose the signal every couple of seconds. I am typing this message from the TV and it is very frustrating because it has taken me about 5 minutes just to type a simple message.

Any ideas about why my TV is doing this?

Oh yeah... and my TV is a 47" Philips LCD HDTV. Here is a link to some of the specs.

http://salestores.com/philip58.html

Also, could it be my PSU that is not getting enough power to the GPU? I have a 585 Watt PSU.

you could try a new cable, a hdtv needs to 'handshake' first when using HDMI (thats why it can take an age to turn over to a hdmi port) so if the cable was faulty it would need to handshake everytime the monitor lost connection causing a minute of black screen or no signal.