This is the environment: Several Win 2003 SP 2 servers and several Win XP SP2 & SP3 clients. All in the same LAN. Firewall is disabled everywhere. No recent Windows updates or configuration changes. This is the problem: Since last Thursday, I log on to any other server or workstation as any regular (non-admin) user and I fail to be able to open ADMIN SHARES ONLY (namely \\server1\c$, \\server1\e$ and \\server1\admin$). The error message is: "\server1\c$ is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions. Multiple connections to a server or shared resource by the same user, using more than one user name, are not allowed. Disconnect all previous connections to the server or shared resource and try again." I can, however, open the same shares if I use FQDN or IP address: \\server1.domain.local\c$ \\172.0.0.1\c$ Other shares do not have this issue and I can open them without any issue. Any ideas or suggestion would be truly appreciated. Thank you in advance.