I am having a problem that only occurred after installing the fglrx proprietary driver through the additional drivers app.
The exact same issue is described in this question, however it's closed.
When I boot up my computer, once I get to lightdm login screen I will start typing my password, and upon the entering of two of my password characters "n2" the screen will start displaying some corruption in the very top edge of the screen, then after I hit the number 2, lightdm seems to crash and it will restart and everything is fine, I can login from that point.
So the issue is, every time I reboot, I have to login once, allow lightdm to crash and restart, then login as normal.
The issue did not occur prior to installing fglrx, and has happened through several reinstalls.