After installing the Feisty Beta on my Inspiron 8600c (LCD with 1280x800 resolution, ATI M10 chipset), the GDM login and the main X desktop both display a pulsing pattern of red, green, and blue horizontal lines throughout the display. This appears to be an indication of some kind of refresh rate problem, although the display is supposedly set at the correct refresh rate. In addition, the native resolution is improperly set at 1024x768; when this is changed to the correct 1280x800 resolution, the desktop literally splits in half (i.e., there's two distinct blurry regions on the left and the right sides of the screen) and becomes unusable. Enabling the proprietary drivers doesn't fix the problem. I'm still working the problem, but the fact that this occurred out-of-the-box on such a common system/hardware configuration probably makes this a bug.
Thank you for taking the time to report this bug and helping to make Ubuntu better. You reported this bug a while ago and there hasn't been any activity in recently. We were wondering if this is still and issue for you? Thanks in advance.