Word - line appears and disappears

[Stacey755]

I've created a Word document which contains a couple of small tables. The cells have a background fill, and one table has two columns. One column contains a PNG file. Sometimes a key line will appear at the bottom of the cell. Then disappears with the ZOOM function. The line should not appear, it does not print and it doesn't appear when the file is saved as a PDF.

See below, why is this happening?

[#2]

This is an artifact of your display and resolution.
I understand that it may be annoying but why does it matter?

[#3]

Because it's annoying and the client doesn't understand why this happens