Network Share Drive

This is the problem I am facing in my environment, few of my user are able to access the share by this method \\servername\share$ but when they mapped as a drive they are not able to access it (net use * \\servername\share$). The error they are obtaining is Access denied.
Issue here is the rest of the user are not not facing this issue. They are able to do in both ways.

I have asked the user to try from other user pc, same issue. Currently we have 8 to 9 user having this problem and they are from different sites. I am afraid if it will increase to more users.

The File and Print server is clustered and we are accessing based on virtual cluster name.
This cluster server was rebooted twice.
The resources has been moved to both nodes and it is still the same.
User able to ping the cluster nodes, user able to ping the virtual node, no issue in name resolutions.
OS is W2K3 R2.

Please advise what else I can check. In term of permission everything looks ok. User when they map from run -> \\servername\share they are able to open the files in the server only when they map as a network drive it is not working, the moment they double click the drive it says "access denied"