This solution applies to many problems, but this one in particular. If you get a yellow screen of death when trying to run a Web Application in IISx that you just renamed, then chances are you didn’t delete the old assembly from the bin folder prior to running the new one. Some additional detail about the yellow screen of death is it mentions something about a bad image format exception. That exception is always related to an assembly that .Net cannot load properly.
Simply put, delete the old assembly from your web application’s bin folder. That should fix the problem.