Lightroom crashes when png fils is used for water mark

Question

When I use png files, lightroom 5.7 crashes (windows 7 64 bit). With the plug-in Mogrify it works, but not with lightroom itself.The dng fil can be imported into the lightroom catalog without problem. But it cannot be loaded for the identification table (lightroom crashes). I had this issue already in lightroom 4.
Thanks for any ideas to solve this.

Answer 1

I opened and resaved the PNG with Photoshop and it didn't crash LR, so it seems your scanner is producing PNGs that aren't quite compatible with Lightroom.
Instead of me uploading files after editing in Photoshop, you can use an online editor like Pixlr to edit your own PNGs that won't crash Lightroom:
I used the following steps in Pixlr to convert ABC.png to a transparent background PNG that had black writing then another with white writing:
Open apps.pixlr.com/editor/ Online Photo Editor | Pixlr Editor | Autodesk Pixlr in a browser, I used IE 11
Click Open Image from Computer
Browse to and Open ABC.png
Double click the padlock symbol in the Layers panel to convert Background to Layer 0
Select the Magic Wand tool - over at the left
Turn off Anti-Alias and Contiguous checkboxes up top if necessary because you want all the background removed and clean edges on this B/W PNG
Click on a white area outside of the letters, notice that the insides of the A and B are also selected because Continuous is turned off
Hit the Delete (Del) key, notice that the background turns from white to a checkerboard pattern indicating transparency
Use File / Save... and save this black-letter copy with a new name (e.g.  ABC_black.png) to your computer, somewhere, as filetype PNG - Transparent, Full-Quality
Use Adjustment / Invert to change the letters to white, notice that the transparency remains
Use File / Save... and save this white-letter copy with a new name (e.g. ABC_white.png).
That's it.
Obviously you can do more things in this editor, but for the simple task of making transparent background PNGs from a scanned PNG that's all you need to do.