The error you get, namely 12571, maans breakdown of communications in the two-task layer.

Tha following instructions due to Metalink might help you:

- Shutdown the database
- Stop the listener
- Remove all the *.dat files in the c:\orant\otrace80\admin directory
- Specify the parameter HASH_JOIN_ENABLED = FALSE in the file
INIT(sid).ORA file
- Specify the parameter EPC_DISABLED =TRUE in the registry
(REGEDT32 -> HKEY_LOCAL_MACHINE -> SOFTWARE -> ORACLE)
- Restart the database
- Specify the parameter TCP_KEEPALIVE in the Windows NT registry

HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Tcpip/Parameters

Edit - Add value : KeepAliveTime (REG_DWORD)

Decimal -> 180000 (for example = 3 minutes)


- Edit the file listener.ora. Configure the parameter
TRACE_LEVEL_LISTENER = OFF

- Remove unused protocol addresses, like Named Pipes and SPX, from the LISTENER.ORA file
- Start the listener
- Specify the SQLNET.EXPIRE_TIME = 0 parameter in the sqlnet.ora file

- Monitor your network