You can see the error message I receive on this screencast when I try to open a Briefcase on my external HDD in Windows 7 Ultimate 64-bit:
It has always worked fine to open this same Briefcase on my old laptop that run Windows XP Pro 32-bit. And all the other, normal, folders can be opened on my new laptop with Windows 7 Ultimate 64-bit. But not this Briefcase. What can be the reason and is there any solution to get this Briefcase accessible so I can open it?