Visual Studio Unit Test and Code Coverage Error

Hello,
I am randomly receiving the error: "The agent process was stopped while the test was running" when running Unit Tests for a C# project.  It is strange because if I select different tests to run, some of the ones that gave the error previously, may pass.
Also, when I try to check the Code Coverage results, I get the error: "Cannot find any coverage data(.coverage or .coveragexml) files.  Check test run details for possible errors).  I have Code Coverage enabled for both the .exe and .dll I am testing.  The TestResults folder being created when the tests are run only creates an Out folder and no In folder.  I also get this error sometimes when trying to view the Code Coverage results:  "Code Coverage Analysis engine threw exception: The process cannot access the file 'data.coverage' because it is being used by another process.