Windows 7 - UNC Shares empty but mapped drives not

The problem I am having is that shares on my dlink DNS-323 are showing empty on my windows 7 desktop, but if I map the same shares as drives I can access the files.

The shares are enabled with guest access so I don't need a password. If I browse to, say \\storage-server\My Photos I just get what looks like an empty folder. I see the same thing if I go through Network->Storage-Server->My Photos in the explorer sidebar.

The strange thing is if I map one of these shares as I drive I can magically see all the files. I don't want to map all my shares because I have a lot of apps configured to use the unc path to them.

I should note that this situation does not occur on my Win XP laptop. I can browse the unc shares on my DNS-323 just fine using that.

Any suggestions? I'm baffled. This happened after I shut down both the PC and the NAS for a period of about 4 days.