Grey border around linked Excel chart appears in Powerpoint Slideshow

Hi All,

I have a linked Excel Chart in a Powerpoint deck. There is no grey line around the Excel chart when viewed in PPT's normal edit mode, but in Slideshow Mode there is a thin gray line around the chart.

In Excel, I've already made sure that the Chart Area and the Plot Areas have no border lines.

What else should I check?? Is this a PPT issue?

Many thanks!

Jay