I have very similar problem. Flickering, white & black stripes and sometimes local screen fading. Any display movement caused change of flickering. It was OK after 3 reboots. The problem occurred again - when laptop was cooled - strange. I thought it was hardware problem and my display or GPU was leaving me (recently I've ordered new laptop).
I've booted (USB-way) an older distro - Ubuntu 10.04 - and problem was gone. Not entirely - strange thing is that the bug shows up even at "BIOS startup".
Conclusion? It's definitely latest Xorg driver bug. Older versions worked perfectly and the bug has showed up after October 12' upgrade. Not sure which one of Xorg packages caused this bug.
My guess - downgrading Xorg driver or reinstalling and fixing it's older version should solve the problem. I hope the nearest future Xorg upgrade will repair this bug.
I don't understand this buggy upgrade since I was using Ubuntu 12.04 "LTS". Have tried Lubuntu 12.10 - still the same problem. OK, but why at the "LTS"?
Ubuntu 12.04/Lubuntu 12.10, HP Compaq 6715b, CPU: AMD Turion 64 X2, GPU: ATI Radeon x1250