Share Mac Files (Yosemite) with Windows
I had a similar issue and this post solved it for me:

https://discussions.apple.com/message/26964292#26964292

It may be the same discussion that Tetsujin references, but the setting to use is NOT "Send LM &amp; NTLM - use NTLMv2 session security if negotiated" -- you should use "Send NTLMv2 response only". After I made that change, I connected to the share, put in my Mac username &amp; pwd, and it connected.