Shared Folders

Accessing shared Windows folders in Sun (Oracle) VirtualBox

I've used Sun VirtualBox (Now Oracle VirtualBox) for a couple of years as a handy way to run Linux on my Windows-based laptop.  It broke a while back and I only just got around to reinstalling it using the new 4.0.0 release - and found shared folders didn't work out of the box.  I could set one up - and I could see it - but it wouldn't allow me access - I got the following error:

You do not have the permissions necessary to view the contents of "sf_virtualbox_sharename"