Installed Kubuntu Desktop on Ubuntu 12.04 and now have lockup with scrambled screen.

[carlwilkey]

I installed Kubuntu Desktop on an existing Ubuntu 12.04 LTS laptop also running Windows 8.1. When I rebooted, it would start to load and then lockup with a scrambled/garbled screen. I had to turn off the computer and restart it. I then held down the shift key to get into the boot manager. I selected some of the diagnostics to try to repair what ever was happening. I then allowed it to boot up normal out of recovery mode and it worked fine. I then rebooted it and the same thing happened, I got the lockup and scrambled/garbled screen. I turned off and turned back on and held the shift key down and I then selected boot normal and it went just fine. Any ideas on what could be happening?

Thanks,

Carl