.NET Unit test throws file not found exception (Microsoft.VisualStudio.QualityTools.Common could

I have created a test project (C#) and when I try to run the test (debug selected tests) from the IDE (VS 2005) I get the exeception

Could not load file or assembly

> 'Microsoft.VisualStudio.QualityTools.Common,

> Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one

> of its ..

How can I fix this. Am I missing any references ?

I have Team Explorer installed on my machine.

Thanks

prad_kav