HOW TO RESOLVE IT
-----------------
1-MAKE sure that all tablespaces are online and all datafiles are
online. This can be checked through v$datafile, under the
status column. For tablespaces associated with the datafiles,
look in dba_tablespaces.

If that still does not resolve the problem then

2-PUT the following in the init.ora-
event = "10015 trace name context forever, level 10"

Setting this event will generate a trace file that will reveal the
necessary information about the transaction Oracle is trying to roll
back and most importantly, what object Oracle is trying to apply
the undo to.

3-SHUTDOWN the database (if normal does not work, immediate, if that does
not work, abort) and bring it back up.

Note: An ora-1545 may be encountered, or other errors. If the database
cannot startup, contact customer support at this point.

4-CHECK in the directory that is specified by the user_dump_dest parameter
(in the init.ora or show parameter command) for a trace file that was
generated at startup time.

5-IN the trace file, there should be a message similar to-
error recovery tx(#,#) object #.

TX(#,#) refers to transaction information.
The object # is the same as the object_id in sys.dba_objects.

6-USE the following query to find out what object Oracle is trying to
perform recovery on.

select owner, object_name, object_type, status
from dba_objects where object_id =