Installed linux-image-2.6.19-7 this morning and it is able to boot. So the problem seems resolved (for me ;)
-- [feisty] [linux-image-2.6.19-6] BUG: soft lockup detected on CPU#0! https://launchpad.net/bugs/72895 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs