Trying to connect to a Windows XP computer became just about impossible. John and I had shared a folder. Given permissions and returned to a Vista, 7 or 8 computer. We went to start and RUN, enter the UNC \\computername to the XP machine. We got a prompt and entered the username and password and hit enter. Again we were met with a prompt….and again and again.
Solution: Windows XP’s time and date were off. Simple fix. Only took an hour.
Also make sure that NetBIOs over TCP/IP is enabled.