UNIX for Dummies Questions & Answers

Waiting for dispatcher 'D001' to shutdown
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.
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Waiting for dispatcher 'D020' to shutdown
Then
Waiting for shared server 'S010' to die
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Waiting for shared server 'S059' to die
All dispatchers and shared servers shutdown
Mon Mar  1 02:19:04 2010
ALTER DATABASE CLOSE NORMAL
Mon Mar  1 02:19:05 2010
SMON: disabling tx recovery
Mon Mar  1 02:19:23 2010
SMON: disabling cache recovery
Mon Mar  1 02:19:23 2010
Shutting down archive processes
Archiving is disabled
Mon Mar  1 02:19:23 2010
ARCH shutting down
ARC0: Archival stopped
Mon Mar  1 02:19:23 2010
ARCH shutting down
ARC1: Archival stopped
Mon Mar  1 02:19:25 2010
Thread 1 closed at log sequence 6678
Successful close of redo thread 1
Mon Mar  1 02:20:48 2010
Completed: ALTER DATABASE CLOSE NORMAL
Mon Mar  1 02:20:48 2010
ALTER DATABASE DISMOUNT
Completed: ALTER DATABASE DISMOUNT
ARCH: Archiving is disabled
Shutting down archive processes
Archiving is disabled
Archive process shutdown avoided: 0 active
ARCH: Archiving is disabled
Shutting down archive processes
Archiving is disabled
Archive process shutdown avoided: 0 active
Mon Mar  1 02:21:03 2010
Errors in file /oracle/app/oracle/product/9.2.0/admin/TAXPROD/udump/TAXPROD_ora_2103814.trc:
ORA-00600: internal error code, arguments: [504], [0x7000000000214D8], 

and then Hangs...If I try to start I get message
Database is already running
If I do shutdown immediate I get the message
Database shutdown in process
Even after an hour I get same message
Only way at this point is to do 
Shutdown abort
Startup
Shutdown Immedaite
Startup