So, after a few days of further testing i'm convinced that the 3.8.0-29 version of the kernel still has some problems.
yesterday, i got the black screen with a blinking underscore again, but after rebooting i got a screen with "/ has to be checked for errors", done, automatic reboot, login worked. then again, a few minutes ago something went wrong again (as you can see in the attached dmesg2.out) and the filesystem was readonly again (well, in fstab is configured to mount as ro when an error occurs, thats no surprise than). i will now try using the 3.8.0-30.43 kernel as proposed by Joseph. ** Attachment added: "dmesg2.out" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1215269/+attachment/3785868/+files/dmesg2.out -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1215269 Title: Unable to boot after kenel update (3.8.0-29). To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1215269/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
