Windows 7: Map Network Drive Win 7 to XP

Hello,

A mapped network drive connected in windows 7 from xp pro. sp 3 suddenly disconnect and now not accessible.
i have checked credential manager , network security - LAN manager authentication level on use NTLMv2 session security if negotiated, both computer's date and time are equal and proper, fire wall also disabled in both the pc.

Now when i am trying to reconnect c drive of xp pc from 7 as a map drive it asks user id & password, i tried to enter it doesn't work. Then i tried to connect it from cmd by net use z: \\computer\share but it displays error 86 occurs.



Please help me as soon as possible.