"NOT IN" predicate hangs result

Hi all,
   I recently tried this select statement and it hung my tool:

1)   select count(*) from user_profile where address_id not in (select address_id from address);

Originally, I just thought that it was slow, so I left it over night and when I can back the next morning it
just hung there(eating up CPU cycles). I looked in Celko's book and then tried this and it worked(quite fast):

2)   select count(*) from user_profile up where not exists (select * from address addr where up.address_id =
addr.address_id);

Is this a known problem?

Thanks
Rick