On my Mountain Lion Mac running Fusion 5.01 with a Windows 7 VM I am also unable to connect a USB drive. The same drive can connect successfully to another Windows machine and to the Mac.
I can try to reinstall Fusion 5.01, but I'm not sure what my license is (it was installed by my IT department). If I follow the instructions linked to by kcheon will it wipe out my license? Is there a way to make a copy of the info I need before uninstalling 5.01?
Thanks.