Windows 7: Corrupt iTunes files in Windows Media Player

We just had a Dish Hopper installed and tried using their Home Media program which looks at Windows Media Player for music. I can play the music from 2 of my 3 computers but the 3rd one won't play.
I checked the 2 computers and I can play the music from there. When I try the 3rd computer I get: The file you are attempting to play is missing or corrupt or not in a location that is currently not available.
Years ago we had the same problem with iTunes but I don't know what I did to fix it.
I removed WMP and had to "turn Windows Futures off" and WMP was available, the problem is it is still linked to the corrupt files.
How do I remove the corrupt files and direct WMP to the correct location?

Hi my name is Mike Houston a Social Media Representative at DISH; I see you have had the Hopper installed recently and you are trying to use the Home Media program that looks at Windows Media Player for music. What software version are you using on the 3rd computer? I will provide you a link explaining the sharing of Windows Media: Sharing media on a network using Windows Media Player. If you would e-mail me with any further DISH questions about the Hopper I am more than happy to answer them; micahel.houston@dish.com

Hi Mike,

For some strange reason I did not get an email telling me you had replied.

I figured out the iTunest file that Windows Media Player uses on the 3rd computer was corrupt and Apple helped me fix it.

Unfortunately now computer 1 has dissapeared from Home Media Device list.

Computers 2 and 3 have the WMP icon and work ok. I went to all 3 computers WMP and they all work.

I know Sharing is working and verified it by going to Network\Network and Sharing Center shows all 3 computers, the Dish Hoppers and Dish Joeys and the router are all listed.

Computer 1 is Win 7 64 Bit desktop, computer 2 is a Win 7 32 bit laptop and computer 3 is a Win 7 32 Bit Desktop. I don't know how to determine what version of WMP they have but it came on the Windows 7 Home Premium Discs install around Nov 2012.

I really appreciate your help getting computer 3 on the Device List.

I did not make myself clear. Everything on my network is shared and 2 of the 3 computers show up on my Dish system.
I must have uninstalled Media Center on the 3rd computer, I searched the computer files and see nothing about media center.
I went to Windows Features to turn on Windows Media Center and Windows Media Player and they are both checked. My conclusion is I stupidly uninstalled them.
Now I need to find a site to download Windows Media Cente and Player. I found 3rd party sites that also include a bunch of junk and I won't do that.

HELP!!!!!