Hi,
Try resetting the device as listed below:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00489814&lc=en&cc=us&dlc=en&product=5070121#N63
If the same persists after completing these steps, it will more likely be necessary to service the printer, HP's contact detils can be found below:
http://www8.hp.com/us/en/contact-hp/ww-contact-us.html
Shlomi