Strange stripes/checks appearing and removing pixels from images

Hi,

Just wondering if anyone else is having this problem with Photoshop CC, I have done this moodboard several times now and each time this glitch has appeared, both times when scaling up a photo. When I delete this grey striped layer it removes pixels from the pictures on the board and I have to start all over again. It happened to all the psd files that I had open at the time. Does anyone have any ideas/help as this is for a deadline?!

Many thanks!