I found the solution for my problem, at least: somewhere in the incremental changes in the 2.6.20.* kernels, the method of determining uuid must have changed: my fstab contained an *almost* identical fstab to what the latest kernels identified the disk as (see screenshot of Gnome disk properties and fstab extract
I changed the fstab with the new uuid and the reboot worked fine!
I found the solution for my problem, at least: somewhere in the incremental changes in the 2.6.20.* kernels, the method of determining uuid must have changed: my fstab contained an *almost* identical fstab to what the latest kernels identified the disk as (see screenshot of Gnome disk properties and fstab extract
I changed the fstab with the new uuid and the reboot worked fine!