I'm using Ubuntu 14.04 on external disk and 2 computers with ATI and NVidia driver each. Actually I'm using nvidia proprietary as main driver and did not install ATI driver. But after upgrade a day ago, unity just showing some weird stuff, i can't describe here by text but it's looks like just a few shape or triangle in unity launcher and top menu. It's kinda like a game need some 3d acceleration and showing only it's spirits.
Thanks in advance and sorry for my english.