You will have a problem with UTL_FILE in the default NT setup because the WinNT user SYSTEM can not access network drives. A solution is to run the Instance (and possibly Listener) NT services as a non-SYSTEM WinNT user, member of the local administrators group and with "log on as a service" priviledge. It works for both mapped drives and "url" format. (I tested with 8.1.7.4 under NT 4.0 SP6a). You should think about impact of password changes though!