I am having the same issue. I have Ubuntu 14.04 server running that I have been running forever, well as long as it has been out. Before that I ran 12. I have been using Samba for years without any problems. No withing the past two days it has stopped working. I can connect to the share, but when I try to access any folder in it. I get the following message on my windows 7 box: Windows Error

The only thing that I did was apply updates to Ubuntu, nothing to windows. If I can provide any more information to assist in clearing this up let me know.

I forgot to mention. I also configured Samba to accept root login. I was able to log into the share, but couldn't access any directories. Same as regular user.