dear reddy,

Let me give some more details.

1) The database is in unix environment and the client is windows based.
2) In the same server two databases are existing. One database I am able to connect through the client. Where as one it is giving the error as I mentioned.
3) I have simulated by increasing the shmmax value also.
4) the same set up is available in one more server E450 sun server where both the databases are up and people are able to connect to both the database through their respective clients. I have checked up the oracle parameters at OS level in both the servers. coming to the databases it is the cold backup restoration. I am able to bring up the database and connect to the server through sqlplus.

Now can you tell me still any points I have to check. I tried your method also.