John is experiencing a brief flash of vertical lines against a white background on his Android tablet. He's swapped out the tablets more than once and wonders if this is a hardware issue or software issue. Leo says that since John is putting the same apps on the tablets, no matter which model he tries, that points to an app or software issue. Leo suspects that the tablet is making a quick adjustment in the video mode as it does in the app. It could be normal since it goes from tablet to tablet. The common denominator is the user, so that's where he can focus his troubleshooting efforts. He should try adding one app to the tablet at a time and pinpoint when the issue starts. That'll tell him what app is causing it.