Unit Tests Run Concurrently in 5.0?

In our suite of unit tests, different projects build and populate a new instance of the database.  Since upgrading to Resharper 5.0, some of these projects containing tests are run concurrently when I run all tests in the solution.  Therefore, multiple copies of the database are being created on top of each other and the tests are failing.  Is there a way to specify that tests should run serially?  All tests pass when I run the projects individually, but I want to be able to run the entire suite at one time.

Thanks,
Carissa