I have four machines: A MacBook Pro, a desktop running Ubuntu and two desktops running Windows 7 64bit. To make it easier in describing the issue I am having, let's call my Windows 7 desktops as PC-A and PC-B. I have shared folders in both PC-A and PC-B that are accessible from all machines and there wasn't any issue with that until two days ago. All of sudden I can't access shared folders in PC-A from my MacBook Pro (through samba mount). At first I thought it was my wifi connection dropping out but it wasn't. I tried to ping and it was successful. Then I tried to access shared folders in PC-A from my Ubuntu desktop and I can't access them either. But I have no problem accessing shared folders in PC-A from PC-B. Also I have no problem accessing shared folders in PC-B from the other three machines. It seems to me that there is something in PC-A that is blocking access from Ubuntu and MacOSX. I tried to turn off firewall (both windows firewall and third party firewall (Comodo)) on PC-A and that didn't help. I update both PC-A and PC-B regularly whenever windows updates are available. I have tried this and it didn't help Anyone can suggest how to fix or diagnose this issue? Thanks.