I have a G5 Mac running Panther, and I've had a LOT of problems with printer drivers for my HP cp1700 (A3 printer). The Deskjet 950 was no problem. Hewlett Packard have been very bad at upgrading their drivers and I'm sick of them. Luckily I have an Epson scanner - no problems there at all.

The only thing I can suggest is to update the driver (I don't know which version you've got).

HP printer drivers

Here's a link to HP's printer/scanner driver downloads. Version 6.3.4 seems to be the newest, but it fills over 55 Mbytes!!!

Hope that helps, I certainly won't be buying any printers from Hewlett Packard again!