I have a .NET application that is using Google Drive to access the user\'s file. I am able to get the authorization code, and I have been able to exchange the authorization
If you are using the .NET client library (http://code.google.com/p/google-api-dotnet-client/), you don't have to take care of that. The library will automatically request a new access token for you when needed using the refresh token you retrieved the first time.