Firefox just updated to v62.0.3 64-bit (Windows 10 pc). Since the update everything I print in Firefox has these black and/or yellow boxes at the end of the content I am printing. These mystery boxes also appear in print preview. See attached image for example. I first encountered these unwanted boxes on Oct. 3 when I needed to print some eBay invoices as well as a few Yahoo emails. This problem occurs when I print to my HP 6520 Photosmart printer and to MS Print to PDF. This issue does not exist in Chrome or MS Edge. Nor did the issue exist prior to the 62.0.3 update.