I have the same problem printing through netpar to a print server when I use GraphicPublisher (part of TurboPrint). It prints a single page just fine, and then hangs--evidently, the Amiga is expecting some kind of reply from the printer that never comes. The only solution is a reboot.
Printing using TurboPrint's PS: device (and Ghostscript

works fine, however. I think there is probably a bug in GraphicPublisher, and it's been there through many versions of TurboPrint.
--Ray