I hit the error below during startup of my 10.2.0.1 RAC installation running on Solaris X86-64 on VMWare
ORA-00600: internal error code, arguments: [kcratr1_lastbwr], , , , ,, , 
Basically none of the instances start-up with srvctl command and log this error to alert log.
Tried to run manual startup of instances but no chance same error.
Quick search on MOS (yes it was working 🙂 ) take me to the note 393984.1 (no bug number)
It says this is a bug on Enterprise Edition – Version: 10.2.0.1 to 220.127.116.11.0
Solution is manual recovery.
SQL> startup; ORACLE instance started. Total System Global Area 369098752 bytes Fixed Size 2020864 bytes Variable Size 138414592 bytes Database Buffers 226492416 bytes Redo Buffers 2170880 bytes Database mounted. ORA-00600: internal error code, arguments: [kcratr1_lastbwr], , , , , , ,  SQL> recover database; Media recovery complete. SQL> alter database open; Database altered.