This sort of problem isn't unique to Postgres, and is one reason why aD started assigning names to nearly all constraints in ACS 4.
In PG, referential integrity triggers should be dropped automatically when you drop a referencing table, so I would concentrate on the triggers that *aren't* anonymous in this case. Try to track it down to the trigger name in one of the .sql files.
This is tedious, no doubt. This is one reason why packages should provide well-bundled "drop" sql scripts. The package/ACS 4 approach tries to do this but it isn't complete in the Oracle version supplied by aD. ACS 3.2 (the source for OpenACS 3.2.5) didn't even try.
For better or worse, you're seeing one reason why aD tried to get this right via *drop* scripts in ACS 4 and why our OpenACS 4 project will try to solve the problem after we've ported the existing code.
