Windows XP Not access from Windows 98 in LAN

i get problem from last few day. In my server0client network some windows 98 pc does not access windows xp pc in lan.
Please help me for proper sollution.
i get an error like
\\Pc name
An extended error has occured.
or
\\xx.xx.xx.xx
The logon server could not found.
kindely give me a proper sollution.