I am consistently getting this error with VS 2013:
Could not copy \"C:\\pagefile.sys\" to \"bin\\roslyn\\pagefile.sys\". Exceeded retry count of 10.
I've found a different solution to this error.
In my case I had been moving around a project within my solution (I put it in a subfolder). My references to packages (located in %solutionfolder%/packages) in the project file were broken and I fixed them manually.
However, there are two supplement imports that I forgot:
I first updated the first one from ..\packages to ..\..\packages (lazy as I am). Building the project after that gave me the pagefile.sys error.
Updating the second import (same change: ..\packages to ..\..\packages) solved it for me.