At the code level what happened pmon was operating and went to translate oracle_home and it couldnt...Maybe the image got
corrupted in memory somehow? Maybe the image ran out of memory -- although we would see ORA-4031's ect in that case or
USUALLY you see a ORA-7445...so this is REALLY rare and weird. Last report of this was on V6 of Oracle.
Now, here is something we can do, we can set an errorstack event so IF it happens again, we will have more info. Next time you
restart the instance, or you can do it while it is running, do one of the following:
*Dump ERRORSTACK on a given error:
init.ora: Eg: event="7254 trace name ERRORSTACK level 3"
running instance : Eg: alter system set events '7254 trace name ERRORSTACK level 3';