Oracle connection problems

[John Sinues]

I installed Oracle 9i as administrator of the local machine and can successfully establish a connection while logged on as administrator. However, when I log off and log in as myself onto the domain, I cannot connect. I've received both the

ORA-12571: TNS packet writer failure

and

ORA-03113: end-of-file on communication channel error

errors. The database and TNS name services are running.
tnsping reports:

Z:\>tnsping 192.168.1.100
TNS Ping Utility for 32-bit Windows: Version 9.2.0.1.0 - Production on 03-NOV-20
03 11:48:42
Copyright (c) 1997 Oracle Corporation.  All rights reserved.
Used parameter files:
d:\oracle\ora92\network\admin\sqlnet.ora
Used HOSTNAME adapter to resolve the alias
Attempting to contact (DESCRIPTION=(CONNECT_DATA=(SID=*)(SERVICE_NAME=192.168.1.
100))(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.1.100)(PORT=1521)))
OK (30 msec)

sqlplus scott/tiger reports:

Z:\>sqlplus scott/tiger
SQL*Plus: Release 9.2.0.1.0 - Production on Mon Nov 3 11:50:55 2003
Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.
ERROR:
ORA-12571: TNS  packet writer failure

Enter user-name:

The sqlnet.log file reports the following error:

Fatal NI connect error 12631, connecting to:
 (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
  VERSION INFORMATION:
TNS for 32-bit Windows: Version 9.2.0.1.0 - Production
Oracle Bequeath NT Protocol Adapter for 32-bit Windows: Version 9.2.0.1.0 - Production
  Time: 03-NOV-2003 12:25:20
  Tracing not turned on.
  Tns error struct:
    nr err code: 0
    ns main err code: 12631
    TNS-12631: Username retrieval failed
    ns secondary err code: 0
    nt main err code: 0
    nt secondary err code: 0
    nt OS err code: 0

Any ideas what is preventing users of the domain from connecting to the Oracle database that was installed on the local machine and how I can fix this?
Specs: Win2K SP4
Oracle 9i
512 MB RAM
50 GB HDD
TIA,
- John
[ November 03, 2003: Message edited by: John Sinues ]
[ November 03, 2003: Message edited by: John Sinues ]
[ November 03, 2003: Message edited by: John Sinues ]

[John Sinues]

I think I resolved the issue. I commented out

SQLNET.AUTHENTICATION_SERVICES= (NTS)

from sqlnet.ora. Now it looks like I can connect.

[SJ Adnams]

you are running bequeath protocol "PROTOCOL=beq" which means people from the domain should not be able to connect...
are you still having problems?

[John Sinues]

Commenting out the above line from the sqlnet.ora file resolved the problem.