Shared Resources , Showing up some time, then dissappearing.

Hi, I'm having some trouble setting up some shared folders on Windows Server 2008 Standard x64, whenever I share the folder, it shows up in the network, and I have access to it, but after some time , it shows up, but I can't access it anymore, I have also noticed, the remote desktop sessions, I open while testing , close everytime the issue with the folders happen. At first I tought it was a network problem, so I ran an extended ping while testing, but it doesn't seem to lose any packets when the shared folder can't be accessed.

Any idea of what could it be?