Long running request getting ORA-1555:snapshot too old error

Hi All,

From the past few months we are getting the error for long running request like the below...

+---------------------------------------------------------------------------+
Inventory: Version : 11.5.0

Copyright (c) 1979, 1999, Oracle Corporation. All rights reserved.

EMRIGRN module: EMRI Goods Receipt Note
+---------------------------------------------------------------------------+

Current system time is 04-JAN-2012 13:07:51

+---------------------------------------------------------------------------+


+-----------------------------
| Starting concurrent program execution...
+-----------------------------

Arguments
------------
p_organization='203'
P_REPORT='Y'
------------

 Current NLS_LANG and NLS_NUMERIC_CHARACTERS Environment Variables are :
American_America.US7ASCII

'.,'

ORA-01555: snapshot too old: rollback segment number 1 with name "_SYSSMU1$" too small
     from  ==> rcv_shipment_headers a, rcv_shipment_lines b,RCV_TRANSACTIONS C,po_line_locations_all d

Report Builder: Release 6.0.8.25.0 - Production on Wed Jan 4 13:07:53 2012

(c) Copyright 1999 Oracle Corporation.  All rights reserved.

Enter Username: 
+---------------------------------------------------------------------------+
Start of log messages from FND_FILE
+---------------------------------------------------------------------------+
+---------------------------------------------------------------------------+
End of log messages from FND_FILE
+---------------------------------------------------------------------------+
Program exited with status 1
Concurrent Manager encountered an error while running