Unable to login

Hi,
I cannot login to an Oracle 9i server from a remote system using “sys@alias/password as sysdba”. The error generated is invalid username/password (ORA-01017) even thouh the username,password and alias are correct. There is no problem with the alias because I am able to connect as a different user. Here are some extra details.
a) remote_login_passwordfile=exclusive
b) Oracle 9i server is on Win NT platform
c) My client is a Win 2000 system
d) Client, server are in two different domainsand there is no relationship between the two domains.
Can somebody solve my problem.
Burzin