When trying to access a shared resource located on a server, you may be presented with the following error, even though you are certain that there are no other connections to it:
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.
This can be fixed by simply restarting the Workstation service on the computer that is trying to access it (not the server). Go to Services, go down to ‘Workstation’, right click it and restart. The problem will be fixed and you can now access the share.