Try actually powering down computer and printer first.Remember the normal power button on vista usaully only puts computer into sleep mode and you need to click on right facing arrow beside power button (in Start Menu) to ascess shut down.Then start up and recheck. If this does not work, it may be printer fault. Im not familar with your exact printer but perhaps you loosened printhead/cartridge connections or spilt ink down the back of same. I would remove each print cartridge in turn, clean its connections only if necessary and check and refit.