I have a problem that's occurred twice to me now, and I have no clue as to why it happens. Basically I create a web forms project with authentication using .net 4.5.2.
I then create a page with a Wizard Control with some steps that uses the default master page. At some random point during my debugging, the styling stops working in the debugging browser, and then stops working within Visual Studio as well. I can see that when I'm in the design view of the Site.Master file the styling is broken, but I have not touched the Site.Master file whatsoever.

If I create a new project, and copy all of my files from the broken styling project into this new project, the styling works again, and I have no idea why this is happening.

The site menu on the master page file, instead of getting styled, I get some SriptManager - Unnamed 3 (first screenshot)

Normally, it would look like on the second image. Anyone has any idea why this might happen?