How to solve ORA-011033: ORACLE initialization or shutdown in progress
ORA-00600 is Oracle's generic message for un-handled internal exceptions i.e. bugs.  Usually they require us to raise an SR with Oracle Support.    This can be a problem for sites who are using Oracle without a support contract.  In that situation we are thrown on the resources of the internet.  

The problem you are experiencing is due to a corrupted block.  The top result in Google offers a simple workaround: find out more. 

SQL&gt; shutdown immediate;
SQL&gt; startup mount;
SQL&gt; recover database;
SQL&gt; alter database open;


(Of course, this is only a solution if you are running in archivelog mode, and so can recover the lost block).