>I'm having some problems with the AAppTest and the Object Test Bench. When I try to invoke a method on my object I get a message that the project needs to be rebuilt. After rebuilding the project I still get the same message.
>

If I remember right, this is a bug in Visual Studio. Does your solution contain a web application? I think either excluding the web app from the project, or setting another project to be the "start up" fixed it for me.

(after a bit of searching). Here's another suggestion:

Turn this setting on:

Tools > Options > Projects And Solutions > Show Advanced Build configuration