Multiple connections to a server or shared resource by the same user, using more than one user name, are not allowed.

Samba Error when trying to connect to a shared folder on local ubuntu samba server:

\\192.168.1.34\sharename 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.

Resolution:

C:\> net stop workstation /y
C:\> net start workstation

Note the /y flag will force the service to stop even if this will interrupt existing connections. But otherwise it will prompt the user and wait.