The problem is clear, you have a problem with your file encoding, If am not mistaken the word in the Text property up there is an Arabic keyword which requires Unicode encoding.
Change your file encoding to Unicode, by doing the following:
Open the XAML file you have problem with, go to File > Save As
Click on the small down arrow at the save button to select the encoding
To Change the encoding try this
Check out the link below. http://msdn.microsoft.com/en-us/library/aa468560.aspx
Change the XAML file encoding to "UTF-8" , you can use Visual Studio to Save File As and then change the encoding.
The problem is clear, you have a problem with your file encoding, If am not mistaken the word in the Text property up there is an Arabic keyword which requires Unicode encoding. Change your file encoding to Unicode, by doing the following:
Open the XAML file you have problem with, go to File > Save As
Click on the small down arrow at the save button to select the encoding
Select Unicode save and replace your old file.
This should solve your problem.