I tried to show a friend SilverlightDesktop recently and when he went to the page it didn't work! He received an error message about an illegal xml character in the .xap file.
Ouch!.
Turns out he had Silverlight 1.0 installed but not Silverlight 2.0 installed. To make matters worse, when I tested this at home I discovered that if you completely uninstall Silverlight, the link that comes up to prompt you to install Silverlight installs Silverlight 1.0 which doesn't work with SilverlightDesktop.
Fast-forward 2 hours of scratching my head and it came down to a simple line in the control properties for the control that launches the Silverlight application:
MinimumVersion="2.0"
in "SilverlightDesktop\SilverlightDesktop.aspx" change:
<asp:Silverlight ID="Desktop" runat="server" Source="~/ClientBin/Silverlightdesktop.xap" Version="2.0" Width="100%" Height="100%" />
to:
<asp:Silverlight ID="Desktop" runat="server" Source="~/ClientBin/Silverlightdesktop.xap" Version="2.0" Width="100%" Height="100%" MinimumVersion="2.0" />
I have checked the fix into the source control. Expect a released install version next week.