I just checked to verify that demo database file is not read-only.
I believe this is a result of the file being locked for some reason, as SQLServer 2008 R2 basically should work normally
Can you load the demos in Visual Studio and try running the project? Does the error happen again? Can you check the Server bar (typically placed near the Toolbox)? Does it have the Northwind database attached?
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!