OS 10.4 - Problem with accessing a Windows network shared folder on MAC

Currently a few of the Art users in my company who are using PowerMac G5 with OS X 10.4 and up, they are having difficulties accessing a Windows Server 2003 Network shared folder.

These G5 MACs have no problem connecting to that Windows server and opening other shared folders, but only a particular folder is non-accessible.
This particular folder is located in an External Hard disk connected to the server. And the funny thing is other users on PowerMac G4 OSX 10.3 have no problem at all.

Before last week those G5 MAC users also have no problem accessing that particular folder, but this week when they clicked on it nothing happened.

I am not really a MAC expert, would there be some settings on MAC to allow it to view that folder?

Any help would be appreciated.