I am sorry to hear that the printer keeps jamming. Does this happen with a particular type of media like Photo paper or does it result in a jam with all types of media?
If the issue is occuring with a particular type of media then try using a different manufacturer or type of media for the print job. However, if the issue is occuring with all types of media and if you have followed all the steps in the document and the paper jam persists, then the unit will require replacement. If your printer is under warranty, please contact HP support to get a replacement printer.
http://h10025.www1.hp.com/ewfrf/wc/contacthp?cc=us&dlc=en&lc=en&product=4066452