Happens to me, from time to time, too. Especially with resource file changes (resx) that are dynamically compiled.
What helped me is to delete the contents of the "Temporary ASP.NET files" folder. Try IISRESET if some child folders are locked. Also ensure you delete the ones for Framework and Framework64, too.
You finde the folder somewhere similar as in
(sorry, can't find backslash on that MacBook).