As another thing, you could play around with different values for AGPMode to see if that solves it (wrong AGPMode values is a common source of symptoms similar to these with -ati). For more details on this, please see the "ATI AGP Mode Quirk" section at https://wiki.ubuntu.com/X/Quirks
As another thing, you could play around with different values for AGPMode to see if that solves it (wrong AGPMode values is a common source of symptoms similar to these with -ati). For more details on this, please see the "ATI AGP Mode Quirk" section at https:/ /wiki.ubuntu. com/X/Quirks