just curious, i assume your using araknis for the router. next time this happens reboot the router to see if this solves your issue. not sure its a coincidence or not but my office printer ($750) from HP did NOT like the araknis router. I fought and fought with it before giving up and pulling my test router out and putting back in my edge router. I say this because the ONLY thing that would fix it would be to reset the router.

My printer was static and DHCPed but frequently would go to the 169.x.x.x scheme. everything else on the network would be fine. Weirdest thing.

It could also just be the printer is a HP printer and HP printers SUCK...all printers SUCK.