Your situation is almost universal in the WIN NT 4.0 sp 6 METAFRAME 1.8 environment. There are a few issues here:
Printing generally and autocreated printers specifically just simply do not work as they should. To get it to work as well as possible:
1. Never use any printer driver that is not on the WINDOWS NT TSE INSTALLATION CD.
2. Whenever possible configure network printers rather than allowing autocreation of printers
3. It is vitally important to follow these rules. Otherwise you will have occurrences of: printing failure necessitating restart of the spooler; occasional server crashes ( sometimes when an autocreated printer with an improper driver auto-purges ) and occasional profound server slowdowns.