Vertical Print Lines Disappearing in Troubleshooting Posted May 4, 2007 Apologies for taking so long to get back. Been very busy. We are using HP Designjet Printer Driver v6.03.00. I have done a full diagnostic and headclean on this printer. The problem has been happening on most of our PC's since upgrading to 12.5.1 I think. And depending on the PC, it will be better or worse, missing different lines in prints in varying quantities. As well as this, I have had a problem with lines disappearing when I zoom in and out.