Because I can't think of one single version of Mozilla that I've ever been able to print web pages from. Certainly not 1.2, 1.3, 1.4, or 1.6.
Fire up Netscape 4.x and I can print anything I want, but not Mozilla. All I get is a cryptic "Printing failed for some reason" (really? no shit!), or in the latest 1.6 release "an unknown error occurred while printing" (yeah, well thank you very much for the obvious).
Are your printers local or network? What network?