Nexus 7 kernel problem?

[anDROIDer6113]

I wanted to have the tap2wake and slide2wake features, so I downloaded the touchcontrol app but stupidly forgot that I was still on the stock kernel. I don't remember exactly what I pressed, but I was told to reboot and when the device powered up again I was presented with a blue screen with lines through it (picture below) but when it turned on, it was EXTREMELY laggy - a couple of second delay between taps. I have tried flashing another kernel but this didn't work. Any ideas about what has happened?