Can't Add Scripts, even if they are very first in project and brand new

Every time I try to add a script I get the error message in the screenshot below. I get this error message with scripts I create directly in the Unity project before I even begin to add to them. I even get this error when I use scripts from the Unity asset store.

So I’d have to rule out compiler errors since the code is either 1) put in the store because supposedly it’s working or 2) any code within the script has been put in by Unity itself. Also I didn’t drag and drop this script into Unity. Again, I made it by right clicking in the project window so Unity should have no trouble finding it through the directory.

Restarting doesn’t help. Starting a new project doesn’t help.

How is this even possible?

Are you sure that,as the error points out, the file and class names are equal? They have to be exactly the same, upper and lower case letter included. If the class is called MyClass the file must be named MyClass, naming it myClass or Myclass won’t work.