[Feisty] kernel 2.6.20-12 doens't boot anymore

Thanks for taking the time to report this bug and helping to make Ubuntu better. Unfortunately we can't fix it, because your description doesn't yet have enough information.
Please include the following additional information, if you have not already done so (please pay attention to lspci's additional options), as required by the Ubuntu Kernel Team:
1. Please include the output of the command 'uname -a' in your next response. It should be one, long line of text which includes the exact kernel version you're running, as well as the CPU architecture.
2. Please run the command 'dmesg > dmesg.log' and attach the resulting file 'dmesg.log' to this bug report.
3. Please run the command 'sudo lspci -vvnn > lspci-vvnn.log' and attach the resulting file 'lspci-vvnn.log' to this bug report.
For your reference, the full description of procedures for kernel-related bug reports is available at http://wiki.ubuntu.com/DebuggingKernelProblems . Thanks in advance!

This is the output you wanted me to provide. NOTE: This is from the
last WORKING kernel cause the kernel in question for this bug doesn't
even boot. So there is no way to present you with the information you
want for this specific kernel (2.6.20-12-generic). That's why I
manualy wrote down the last lines of the error message on paper and
then typed them in the bug report in my initial report.

$ uname -a
Linux grinningcat 2.6.20-11-generic #2 SMP Thu Mar 15 08:03:07 UTC
2007 i686 GNU/Linux

Question: Can I find a detailed changelog/diff somewere of the ubuntu
patchsets that are applied to the Feisty kernel? Since the problem
reported here only appeared after the last Ubuntu update I might find
some useful infos in it.

OK my mail attachements got lost so I add them here via LP web interface

Beginning with the Hardy Heron 8.04 development cycle, all open Ubuntu kernel bugs need to be reported against the "linux" kernel package. We are automatically migrating this bug to the new "linux" package. However, development has already began for the upcoming Intrepid Ibex 8.10 release. It would be helpful if you could test the upcoming release and verify if this is still an issue - http://www.ubuntu.com/testing . If the issue still exists, please update this report by changing the Status of the "linux" task from "Incomplete" to "New". We appreciate your patience and understanding as we make this transition. Thanks!