I isolated the problem. I have both kubuntu and ubuntu 12.04b2 installed. Whenever one of them update the kernel, it replaces the grub2 configuration. Anyway, the other (k)ubuntu is detected by /etc/grub.d/30_os-prober and its entries are added to grub menu.
If I select the entry generated by os-prober, there is no problem with VGA. If I use the main entry, I got the problem. The difference from the default entry (generated by /etc/grub.d/10_linux) and os-prober are: recordfail gfxmode $linux_gfx_mode insmod gzio I guess the gfxmode present only in 10_linux entries that causes the problem. Maybe it is related to the fact that my two monitor support different max resolutions. -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-ati in Ubuntu. https://bugs.launchpad.net/bugs/973866 Title: VGA and second monitor on ATI HD 6670 (Dell XPS 8300) is broken To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/973866/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp