I have successfully connected my Dell 1555 to a Panasonic Viera TV (tx-l24e3b), an HD TV, as a second monitor just once, with brilliant results (picture only so far), showing desktop and photos on the laptop, so I know it can be done. I did it without recording what I did - I just tried and it worked!
Now I need to do it again, and a day spent trying has produced no result!
I follow recommendations on several websites including Microsoft:
1. Connect HDMI cable to TV and PC when off, switch on TV first, then PC
2. Use TV remote control to find AV then HDMI2 - blank screen
3. On PC open Display settings
4. In that window showing Multiple displays choose Extend these displays - the PC reads '2. Panasonic TV' [which must mean the cable is OK]. Click 'Apply' then 'Keep changes'
5. TV remains blank ie PC desktop is not showing
6. Open screen resolution, set to 1366x768 (recommended for PC). TV screen remains blank so try other resolutions. Screen remains blank.
I would be very grateful for any help with this, particularly by anyone with the same laptop or TV!!!