I found the cause of the problem. The 'root=' entry in grub seems to cause the problems. If I change it to
kernel /boot/vmlinuz-2.6.32... root=/dev/sda1 ...
the system boots without any problems. The error message from my original report disappears. I can boot any kernel (10.04, mainline, vanilla kernel from Linus' git). Changing the root entry to '.. root=UUID=...' leads to problems in all 10.04 kernels past minor version -20.
I found the cause of the problem. The 'root=' entry in grub seems to cause the problems. If I change it to
kernel /boot/vmlinuz- 2.6.32. .. root=/dev/sda1 ...
the system boots without any problems. The error message from my original report disappears. I can boot any kernel (10.04, mainline, vanilla kernel from Linus' git). Changing the root entry to '.. root=UUID=...' leads to problems in all 10.04 kernels past minor version -20.