I've noticed in our production environment that when I go to the Calculate Code Coverage for Your Organization link in the Setup->Develop->Apex Classes menu that the calculated code coverage is quite different than the total code coverage after clicking on Run All Tests.  Does anyone know which is correct?  Also, when I click on one of the percentages to see the code coverage of a given file, it seems to always say that the file was modified since the last test run.  How can that be when all tests are ran any time a change is made to production?  I'm guessing that the Run All Tests code coverage is correct, but why isn't that data being saved off and pulled when Calculate Code Coverage is clicked?