dv6-2155dx hdmi problems

Well considering your unknown device has nothing to do with your HDMI port, you could try a slightly updated driver. If that doesn't work (and it very well may not) then you more than likely have a busted port.

The last drivers made for your device were for windows 7, but the drivers should still install and work fine. This is the last one made for your GPU: Download Intel® Graphics Media Accelerator Driver, Windows 7* 64, Windows Vista* 64 (exe)
You may want to use DDU before installing the new driver as it cleans out the old driver and the registry very effectively.

Beyond the Unknown device, still cant get my HDMI to work.

Have you tried a different HDMI cable? Did you try the driver Carsomyr found?

The only other thing I can suggest is to test the HDMI port in Windows 7.

Do you have a spare hard drive? You can replace the one now and install Windows 7. If you don't have a spare hard drive you can install Windows 7 in a virtual box.

Another option would be to make a backup image of your entire hard drive. Most people on this site use Macrium Reflect Free. After you created the backup, install Windows 7 and all the drivers. Even if it's not activated, I think it has a 30 day trial period. This should tell you if it's a driver issue or a bad HDMI port.

After you are done with the test, restore the backup image.

I sort of already assumed you tried a different cable, but I guess it is worth mentioning :P Try different cables and try to hook up to different sources (i.e TV, Monitors, etc) but if it fails I would assume the port is bad, particularly if it is a hand me down from someone else...

Actually havent tried another HDMI Cable till today and that was the issue, but wierd both work on an xbox.

Thanks for the update. Glad to hear you sorted it out.