instance consistently crashes after 5th backup

I have done an Oracle upgrade from 11.2.0.2 to 11.2.0.4.

First I upgraded grid software for asm and crs to 11.2.0.4.

The upgrade was successful.

Grid 11.2.0.4 and RDBMS 11.2.0.2 were working fine together in my 2 node RAC for weeks.

SMO backups were working fine.

Then I upgraded RDBMS to 11.2.0.4.

That upgrade was also successful.

Since then, my instances have been crashing on the server that does the backup on every 5th backup.

I have done many tests in my DEV and environment and discovered that if I bounce the instance that is being backed up before the 5th backup, the instances and ASM does not crash.