@johnvan - tysvm for your post! Saved me. If I hadn't remembered seeing it, I'dve resorted to another reinstall of VL. I had upgraded many packages at once on a fresh install after a crash. Wouldn't have known what to suspect, but remembering your post made my first guess the right one.
Ditto johnvan's post, but on my system X just wouldn't start. Downgraded libpng to previous version, and problem solved.