Cannot open mapped network drive

Ok I can see the other PCs/devices on my network just fine. One of them is
just a basic network harddrive.

I can map one of the folders on that drive just fine. Then I double click
on the drive under Computer (in my case it's drive Z. It opens up and I
see all the sub-folders and files in the mapped location.

Now here's the problem. If I double click on any of the folders to open
them, it basically just hangs. The....what I'm assuming is a progress bar
across the top eventually fills up and then just sits there.

If I double click on any of the files, it'll open the app to view that file
(say notepad for instance), but then notepad will just hang without having
read the file. And once again I'll see the progress bar on the explorer
window fill up and then just sit there.

Why can't I access anything on a mapped network drive??? I have three other
PCs on this network. One running XP, one running 2K, and one running 98
(don't ask). All can access the same network drive with no problems at all.

What is the problem here?? I don't have the Windows firewall or anything
like that enabled so I'm not sure of what the problem is.