I have a MacBook Pro 13 running on Mac OS 10.8.4, and I have also installed Parallels 8 running a Windows XP on it. I used to be able to access all my windows files from the Mac side as they would show up with the Parallels logo next to them. I am not sure when and why, but I no longer can't access them. Something also funny happened as now the time synchronization on the Windows side is also acting strange and it is not pulling the correct date/time from the Mac side. Even though, of course, the options for that are all marked on Parallels setup. It looks like for some reason my Windows side lost some connectivity with the Mac side.
I had the same problem after the last update. Re-installing the Parallels tools and relaunching put the mounted virtual drive back in my finder. I hope that helps.
