csproj* Cannot save web project

Question

I have an web project using WebAPI 2 with is compile clean and starts with owin. So everything seam to be ok, but if i open the project properties their is always a star next to my project settings tab. I can save it, (File => SaveAll or Ctrl + s) but the star does not disappear. The resulting problem is that this project cannot be checked in to TFS which shows me an error message that I have to save my project. This project is migrated from vss but the modification problem occured also before the migration

Answer 1

I fiugred it out:

The problem was, that in .csproj the ProjectTypeGuids tag was surrended with comments .....</ProjectTypeGuids>-->

After uncomment the line the project can be saved