That sounds like a problem that showed up last year which was caused by a certain version of Adobe Reader introducing the black lines. As I recall, it started after Adobe started to push users to use their 'cloud' based Reader --which had some inherent problems. I use Adobe Reader v 11 (XI) which is installed on my PC and not cloud based, and works fine.
There are several sites that offer downloads of v 11, as well as some sites that offer other products that 'replace' Adobe Reader (such as Foxit). You can Google for 'pdf reader'. If you do download a version of Adobe Reader MAKE CERTAIN that the description and/or version DOES NOT contain "DC" (which indicates it is a cloud version).
YMMV
