Created attachment 500994 [details]
Screenshot of the white lines

Description of problem:
I have a computer with an Intel GMA 3100 integrated graphic card and an ATI HD5450 graphic card. When I unplug the HD5450 graphic card, Fedora 15 works well. But if I plug in the HD5450 graphic card, there are glitchy white lines above the notification area, and somewhere else, such as the screen shows up when I click on the "Activities" button. These lines also show up when I use the live CD version of Fedora 15 with the HD5450 graphic card. I've also test live CD on another computer with an ATI HD2400 graphic card, but Fedora 15 runs well and no glitchy lines show up.

Version-Release number of selected component (if applicable):


How reproducible:
Run Fedora 15 using an ATI HD5450 graphic card


Steps to Reproduce:
1.Plugin an ATI HD5450 graphic card
2.Boot the computer with Fedora 15 live CD
3.
  
Actual results:
Glithcy white lines show up over notification area.

Expected results:
No such white lines.

Additional info: