I have tried to connect 2 sources (PS3 and Time Warner Cable) to my LCD TV (Sharp 32DA5U) and both are not working. The signal just jaggs around and I get a green fuzz with the PS3. Because both sources are having the same problem it leaves the cable and the TV. I got the tv in 2005 and this is my first time trying to use the HDMI. The HDMI cable is a monoprice 6 footer. I thought I'd ask the HDMI geniouses what they thought the problem was.
The next step of troubleshooting would be to try a different cable (or maybe borrow one from a friend), and similarly try plugging in one of the sources into a different TV (maybe take it to a friend's house who has another HDMI TV). That should help you to isolate the root cause. Please report back on your findings- we're interesting in knowing what it is.