I am working on the first exercise in chapter 27 which spans 897 - 901 and uses the O/R designer to build the objects for the Products table.

I have completed the work and it has run once however when I made a change to Table<Product> from var query I am getting an error regarding the fact that the .mdf cannot be copied.

I tried to download the exercise from the website and the same issue arises. Does anyone know why the sqlserver seems to lock down the file for this exercise?