SQL Server 2008 R2 copy DATA folder

  I use SQL Server 2008 R2 express. How do I copy the DATA folder C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA to another folder? When the copying gets to master.mdf I get following message:


"Cannot copy master: It is being used by another person or program. Close any be using the file and try again."


I use Explorer to copy. I have just rebooted and no other programs are running apart from my antivirus program (Trend Micro).


carl.g.b
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