Try using the IP address of the computer, not the computer name - it seems there is a DNS resolution issue on the internal network - people were having this issue 2 or 3 years ago with Win 7.
This seems to have an explanation on what you see - »answers.microsoft.com/en-us/wind···657fe45c
Answer 11 off this link seems to help too, give it a try
For what it's worth department. I tried ALL the above suggestions to no avail but in my case the following worked for my situation.
Go to Control Panel
Go to Credential Manager on each Windows 7 machine on the network
Under Windows Credentials, type in the name of each machine, username and password
It sounds too simple but it worked for me. The shared files and folders popped right up after this!
Although not for others, that's 2 options for you to test.
Some of the more tech people here maybe able to explain why or why not of this though.--
The only thing necessary for the triumph of evil is for good men to do nothing - Edmund Burke