disable/enable trigger hangs

Hi, I'm using PostgreSQL 8.1.4 and am having some problems with the new
disable/enable trigger command.

First, a question: For a PG8.1 database, is it preferable to use the new
"alter table disable|enable trigger" command as opposed to the old
method of setting pg_class.reltriggers = 0?

I'm assuming the "alter table" approach is preferred, so I converted
some scripts to use the new method. However, sometimes the
enable/disable trigger command hangs when operating on certain tables.
I use the syntax "ALTER TABLE mytable DISABLE TRIGGER ALL;". Any hints
on how to debug this?

Mike