Sharing prblem

Hi,
i am having different domains and workgorup.
one of workgroup having win 2k, nt4 and win98, with all have same username and password.
i shard a folder on win2k and trying to access it form one win98 but i am asked for password (share name is \\username\IPC$ and asked for password) but not able to access the folder. i am able to access the forlder with other win98 system, having problem with only one
what is the proble
how to solve it