I'm not able to access xp system from windows 2000.but I can access 2000 machine from xp.I tried pinging it's working fine.I disabled the firewall,anti virus.but nothing happened.
Any give me a suggestion.

You must grant share and file level permissions on each machine for every account that is to have access. Remember that there are share level permissions and there are file level permissions. As a best practice, it is easier to grant Share level permissions to Everyone with Full Control and control access permissions with File/Folder level security. Always use groups whenever possible and make users a member of the groups.