I have the following:
OS X Mavericks 10.9
Fusion 6.0.2
Windows XP Professional VM
Windows 7 Home Premium VM
The main reason I run the VMs is because I have a couple of dive watches that only have (old) Windows software for downloading their data. I have been using a Windows XP VM for some time without problems but want to Windows 7 as XP will be out of support soon. I recently set up the Windows 7 VM, installed the watch software and the first time I used the software it worked. The next time I went to use it, the applications can't access the shared folders*. I've never had this problem with the XP VM. I can access the shared folders from Windows Explorer. I also found that if I copy just one file (doesn't matter what file) from a shared folder to the C: drive and then start either application, they are able to access the shared folders. Clearly, copying the file changes the state of something which the windows applications are depending on.
* File Open and File Save dialogs do not include Z:
Further information:
Windows XP VM - Hardware Version 7 (this VM was originally used with Fusion 3 and I'm reluctant to upgrade)
Windows 7 VM - Hardware Version 10