I recently changed the namespace in a Silverlight project and ran into lot of problems! Visual Studio was smart to change the namespace in many files, but I ran into this bug and the page will not render
InitializeError- Invalid or malformed application: Check manifest.
I researched this and came across this forum posting:
First I learnt an easy way to look at the XAP file. Just change the extension to .zip and you can unzip it and look in the App.Manifest file. No problem there. Then going through the thread I found the solution as recommended by R. Wiltschek. Quoting him
“In human-readable words, this is what fixed it for me: 1. Open the properties of your project. 2. On the first page, open the drop down list of "Startup object". 3. Select the page your project starts with. In my case, changing the name of the namespace broke the startup object.”
It worked for me!