Oracle export error

Hi

  When I am doing a full export of database. I am getting the below error.

EXP-00008: ORACLE error 3113 encountered

ORA-03113: end-of-file on communication channel

EXP-00008: ORACLE error 1041 encountered

ORA-01041: internal error. hostdef extension doesn't exist

EXP-00000: Export terminated unsuccessfully

I had gone through oracle forum website
(http://forums.oracle.com/forums/message.jspa?messageID=1178529) which had suggested to run the below scripts.

1)catrepr.sql (Removes Replication related objects)

2)catrep.sql (Creates Replication related objects)

3)utlrp.sql (Recompile Invalid PL/SQL modules).

I ran the above scripts ,But the last scripts utlrp.sql hangs in the middle.

Then later if we run the full database export again ...we are geting below error.

EXP-00056: ORACLE error 21560 encountered
OCI-21560: argument 7 is null, invalid, or out of range
EXP-00056: ORACLE error 21560 encountered
OCI-21560: argument 7 is null, invalid, or out of range
EXP-00000: Export terminated unsuccessfully