Refresh the page bypassing the browser cache:
http://en.wikipedia.org/wiki/Wikipedia:Bypass_your_cache
Clear your browser cache, capture the session in Fiddler, and then post the Fiddler session. If you can't post the session to the forum then post it cloud storage, e.g. DropBox, SkyDrive, etc., and post the link here.
I am glad that you have made some progress.
Unfortunately, I have not used the Silverlight viewer application so I cannot speak to how it works. It seems to be some type of configuration issue but I know that you already know that:)
Perhaps someone in the ArcGIS for Viewer Silverlight forum can help you.
Jamal, you can update the URLs used for your services by editing a Map.xml file in any text editor. This file is located in the C:\inetpub\wwwroot\Apps\%AppName%\Config when using the default folder. I am sure you will find out where it is if you are using a non-default path. Just run find and replace in the text editor to change the localhost for the PC name, restart web browser and clear its cache and you should be good to go.