I am attaching a Dell 1530 laptop trunning Windows Vista to this Samsung ln40c550 monitor using a HDMI cable. The TV is new and so far I have it working okay with my cable box (RF in). The tv connection is only intermittently being recognized by the laptop. Pretty much I have to boot up the laptop to get it to see the tv at all, and if the cable is removed or even jiggled it can't tell when it is replugged. The tv is identifying as a Generic PnP monitor in the Device Manager. Is there a driver I need to load for this to work right? Also I am not getting any sound over the HDMI. I have found the button on the laptop that switches monitors between the built-in and external. This is not solving the problem. If I toggle that button when it is not working right the computer tells me no external monitor is attached.

Go to "Sound" from Control Panel, or from right-click on the Desktop and then choose "Personalize" from the menu. Click "Playback" at the 'Sound' app, you should see "Speakers/Headphones" and "HDMI" codecs.
If "HDMI" is there, simply click on it and click "Set Default"
If you don't see "HDMI" right click on "Sound" and click on 'Show Disabled Devices" -- "HDMI" should appear. If "HDMI" is not there, you need to install the HDMI sound driver. HDMI has its own audio driver separate from the audio system of the computer ( Sigmatel, IDT, or Realtek ) . It is incorporated into the graphics card's driver, so first make sure you have the newest version of your graphics card driver. On models with Intel graphics the HDMI audio driver will appear in the Device Manager as "Audio device on high definition audio bus".

Hope this helps.

JB