Window turns transparent when receiving calls or sharing

Here is a screen shot of what the Skype window looks like at the time someone calls me or attempts to share their screen. You can see the bottom and right edge of the Skype window which I have outlined in red. I have to completely end the call and close out of the window, and then re-launch the window to get it to reset. This happens multiple times throughout the day.

Any ideas as to why the window randomly turns transparent when making or receiving calls?

Thanks,

Josh