Backup server issue

Hi everyone,
I have installed and configured ASE 12.51 on Win 2000. The ASE has
been running fine and there is no issue. However, I hav been having
problem with starting the backup server after I changed the charset
from CP850 to iso_1 with nocase. Before changing the Backup server
charset, I have completed the same charset change and sort on the ASE
server without any problem. The backup server starts after changing
the charset, but anytime I reboot the Windows box the service fails to
start.
I have checked the sql.ini file and the backup server using its own
port. There is no port number duplication.
I have discussed this issue with Sybase tech. rep. and so far no
progress. I have applied the latest ebf and I still having the same
problem. I have seen this message in the backup error log:
Jul 23 19:49:41 2004: Open Server Error: 16240.10.0: Net-Library
routine sybnet_listen() failed in srv__start_net
Network error: status = 23 - Net-Lib protocol driver call to register
a listener failed
..
Jul 23 19:49:41 2004: Open Server Server Fatal Error: 16029.20.0:
Failed to start any network listeners
..
Jul 23 19:49:41 2004: Backup Server: 1.29.2.1: Unable to start the
Backup Server. See Backup Server error log for additional
information.
Your help will be highly appreciated in advance.
Thanks,
Majid