Have you seen this issue? It can be very frustrating. You set out to create a new project, put in your first page, build, launch IE and BAM!!! ERROR Could not load Type YourNameSpace._Default. OK, OK, so you go and you check all your src references to be sure that they match your Default Namespace. Hmmm, they're all good. You try to just rebuild the solution. No good! Then after an hour of research, someone suggests trying to re-install the DotNetFramework. Why would I want to do that? Everything else is working fine on my machine. No other projects are having this problem. But what the heck... What do you know, it's working now. But I have no explanation as to why. Can anyone else give me an idea what the problem was here? I can't find an explanation for it. I'm just curious.