IIS 7 The process cannot access the file because it is being used by another process

Had this problem today. It seems this is due to the port (80 in this instance) currently being used by another application. If your running Skype and it was started before the binding to port 80 was created then skype will try to hog port 80. The solution, close skype, rebind the website in IIS to port 80 then restart skype!