Powerpoint printing black and white?

We have a PC with NT4 SP6 and Office 97. When we try to print to an HP Colour Laserjet 4550 the print dialog box is automatically coming up with the ‘print black and white’ box ticked as default. When we remove the tick it appears on the next print. Has anyone else had this problem? I am having difficulty determining whether this is a Powerpoint, HP or NT problem. Any help would be gratefully received!