If you expand a VM and the Windows OS recognizes the new space as unallocated space, there is a quick fix:
Download a freeware program called Easeus Partition Master – http://download.cnet.com/Easeus-Partition-Master-Home-Edition/3000-2248_4-10863346.html?tag=mncol%3bpop&cdlPid=10982635. Run this on the Windows VM and it should show 2 drives. Highlight the one you want to expand, click on (expand/resize), drag divider out to full size of HD and then “apply”. Reboot and it should be fine.