I am using Excel 2008 on a Mac desktop computer with OS 10.8.5.

I added a border to a certain row of cells (a black line underneath the row) in a spreadsheet, and saved the spreadsheet. Now I want to remove that border, but when I do that, the grid-line corresponding to it disappears, too.

Using the standard procedure for making grid-lines visible does not restore it. I should be grateful for advice as to how to solve this conundrum.