Hi Tyson McCall,
The most common reason we see for this type of issue is that you have two instances of ArtOfTest.WebAii installed in your GAC (C:\Windows\Assembly), and you are also using a 3rd party/custom assembly that is targeting the Older version of ArtOfTest.WebAii, whereas the project is trying to use the newest version of the assembly. This would most likely be in-between the two tests that are referenced in the ticket (the test, and the one targeted as a test as step). Look in both of these for an item that would cause this type of conflict.
If you cannot locate the cause, would you be able to provide a copy of this solution within a private dropbox folder (so others can't see the solution, just you and us here at Telerik) for us to take a look at? This would be so we could assist with isolating the issue to a specific test step (within the test that cannot execute as a step).
the Telerik team