Access denied

[C# Programming]

I'm running a little code that should write code to a text file within the application directory, however I'm getting the following error:

Access to the path c:\inetpub\wwwroot\MapFile\Mapped.txt is denied

I'm logged on as Administrator on Windows Server 2008 and running VS 2008 SP1 / .NET 3.5.

Any ideas?

Jon