can someone please reply to this, have the same issue with problem management 7.6.03
i think there is an Sys Application Clean up form exists in ITSM that should take care of deleting the Orphan Tasks....
what it does is there would be records residing on that Sys Application Clean Up form and an Escalation runs and updates that record and passes the trigger on to these child forms (like CHG:Associations, Tasks.... to figure out that if there is any Parent Object does not exist in the system and the Child remains in the Delete Mode, it would delete that record)
This happens for the relationships but if this is not happening for the Tasks pls report to BMC, it has to be fixed in the similar way.
I did report this issue to BMC and was told it is working as designed.
However, this goes against basic database fundamentals of parent / child relationships and to never have orphan records.