Comment 47 for bug 447892

Thank you for testing. I also have no idea why KMS and ACPI seem to be
related. Just thought it would be nice to know for the upstream
developers if turning off ACPI helped. If it doesn't work, it doesn't
work.

Actually, if you back out of xorg-edgers and back to standard Karmic,
you should be able to run without KMS, since UMS support was dropped
only after the driver in Karmic. You can use the ppa-purge script for
that (`sudo apt-get intall ppa-purge` will pull it from the
xorg-edgers PPA, and running `sudo ppa-purge xorg-edgers` will remove
everything from xorg-edgers exept ppa-purge itself). Now with standard
Karmic drivers (and both with Karmic kernel and mainline kernel)
- check if it still freezes with the kernel option "nomodeset" [*]
- check if it still freezes with the kernel option "acpi=off"
It may be that acpi=off turns off KMS and that is the reason it helps,
but if it freezes with nomodeset and not with acpi=off, that would be
interesting.

I think the "low graphics mode" problem you are having may be one of
the bugs mentioned in this post:
https://lists.ubuntu.com/archives/ubuntu-x/2009-November/000650.html
(the ones about gdm).

[*] I looked if you had already done this, but at least I couldn't
find it. It is in situations like this it is really not helpful to
have other people reporting what they have tried. Makes it harder to
find what you did.