You didn't mention what Operating System you are using. Has the printer or OS been recently installed or reinstalled? Also, the printer driver may have become corrupt and need to be reinstalled. If you reinstall the driver be sure to first disconnect the printer and restart the computer or the OS's standard printer driver mayn take control of the printer.
Also, there may be a feaature for text shadowing that need to be deselected. a viruse or other malware may also be causing it.
im usin a hp laserjet 1000 series,the thing is whenever i print a page out the whole page is like discolored,although the document are well printed out there is still like shadows of the alphabets in the background.i have done the cleaning utility several times,but the docs are still the same,i have also clean the inside of the printer.what should i do