ORA-03113 error when testing alias which used to work

I have an alias which inexplicably stopped working last Friday, when I attempt to test the alias I get an ORA-03113 error. I can successfully connect to any of the other aliases in my tnsnames file, and other machines can connect to the remote database specified in the service name (the same one I get the error when trying to connect). I can tnsping the alias and get a response, but cannot connect from this particular machine to the remote database. All workstations are on the same hub, so no network connectivity issues here. Also I tried replacing the tnsnames file on this machine with one from a machine which could connect and still got the error. What gives?

Problem Description
-------------------

You have installed Oracle Server Product on a server. You are
able to connect to the database with no connect string.

SQLPLUS

When you try to connect with a connect string either from a client on
the network or loop-back on the same server:

SQLPLUS @

You receive the following error:

ORA-03113: end-of-file on communication channel.
Cause: An unexpected end-of-file was processed on the communication
channel. The problem could not be handled by the SQL*Net,
two task, software. This message could occur if the shadow
two-task process associated with a SQL*Net connect has
terminated abnormally, or if there is a physical failure of
the interprocess communication vehicle, that is, the network
or server machine went down.
Action: If this message occurs during a connection attempt, check the
setup files for the appropriate SQL*net driver and confirm
SQL*Net software is correctly installed on the server. If the
message occurs after a connection is well established, and the
error is not due to a physical failure, check if a trace file
was generated on the server at failure time. Existence of a
trace file may suggest an Oracle internal error that requires
the assistance of customer support.


Solution Description
--------------------

Remove the PROGRAM parameter from the SID Description in the
Listener.ora file.

Example of an incorrect SID_DESC:

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = ora15.world)
(ORACLE_HOME = u02/oracle/product/815)
(SID_NAME = ora15)
(PROGRAM = extproc)
)
)


Example of a correct SID_DESC:

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = ora15.world)
(ORACLE_HOME = u02/oracle/product/815)
(SID_NAME = ora15)
)
)


Explanation
-----------

When the PROGRAM is specified in the SID_DESC, the listener tries to
pass the connection to the program named in parameter. The connection
fails with no real clues in the client trace and no server side trace
is generated, but the listener shows the connection as established.


Hope this would help you.
Sam

This thread may be closed. The problem that ended up being the root cause of the ORA-03113 error was that a DNS server on the network was reporting an incorrect IP address for the remote host. When this computer attempted to connect it could not resolve the host name to the correct IP address. After correcting the issue with the domain name server the ora-03113 error was resolved. This was a situation where only one alias in the tnsnames.ora file was reporting this error, and the alias had previously worked without fail. Why the DNS server suddenly came up with an incorrect IP address I will may never know. Win2000 and active directory to thank I guess for this problem.