How change target framework for unit test under VS2010?

In my solution (under VS2008) I have few web projects, few class libraries, unit test project.

It seems like during solution conversion to VS 2010 the target framework for UnitTest projects was changed to .NET 4.0

When开发者_运维技巧 I try to change it back (I need to check how system works in .NET 3.5 and compare with current behavior) I am receiving the following error:

Attempted re-targeting of the project has been canceled. You cannot change the specified .NET framework version or profile for a test project.

Why I can't change it? How can I do?

Thanks a lot!

---

Unfortunately, found a negative answer:

http://connect.microsoft.com/VisualStudio/feedback/details/483939/unable-to-change-target-framework-version-on-unit-test-projects

closed as "Won't fix"

http://connect.microsoft.com/VisualStudio/feedback/details/514130/visual-studio-2010-beta-2-silently-upgrades-mstest-test-projects-to-net-4-0

clase as "by design"

:(

P.S. I like one of the suggested workarounds: don't use MS Test :)