Same problem this evening with the last kernel update. This time I have more data.

The update data in the Synaptic history:
 
Commit Log for Thu Oct 22 20:00:33 2009

Les paquets suivant ont été mis à jour :
linux-generic (2.6.24.24.26) to 2.6.24.25.27
linux-headers-generic (2.6.24.24.26) to 2.6.24.25.27
linux-image-generic (2.6.24.24.26) to 2.6.24.25.27
linux-libc-dev (2.6.24-24.61) to 2.6.24-25.63
linux-restricted-modules-common (2.6.24.18-24.1) to 2.6.24.18-25.2
linux-restricted-modules-generic (2.6.24.24.26) to 2.6.24.25.27
nvidia-glx-new (169.12+2.6.24.18-24.1) to 169.12+2.6.24.18-25.2

Les paquets suivants ont été installés :
linux-headers-2.6.24-25 (2.6.24-25.63)
linux-headers-2.6.24-25-generic (2.6.24-25.63)
linux-image-2.6.24-25-generic (2.6.24-25.63)
linux-restricted-modules-2.6.24-25-generic (2.6.24.18-25.2)
linux-ubuntu-modules-2.6.24-25-generic (2.6.24-25.42)

The menu.lst before update:

## ## End Default Options ##

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic
root		(hd0,1)
kernel		/vmlinuz-2.6.24-24-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro quiet splash
initrd		/initrd.img-2.6.24-24-generic
quiet

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic (recovery mode)
root		(hd0,1)
kernel		/vmlinuz-2.6.24-24-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro single
initrd		/initrd.img-2.6.24-24-generic

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-23-generic
root		(hd0,1)
kernel		/vmlinuz-2.6.24-23-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro quiet splash
initrd		/initrd.img-2.6.24-23-generic
quiet

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-23-generic (recovery mode)
root		(hd0,1)
kernel		/vmlinuz-2.6.24-23-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro single
initrd		/initrd.img-2.6.24-23-generic

title		Ubuntu 8.04.3 LTS, memtest86+
root		(hd0,1)
kernel		/memtest86+.bin
quiet

### END DEBIAN AUTOMAGIC KERNELS LIST

The menu.lst after the update:

## ## End Default Options ##

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-25-generic
root		(hd1,1)
kernel		/vmlinuz-2.6.24-25-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro quiet splash
initrd		/initrd.img-2.6.24-25-generic
quiet

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-25-generic (recovery mode)
root		(hd1,1)
kernel		/vmlinuz-2.6.24-25-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro single
initrd		/initrd.img-2.6.24-25-generic

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic
root		(hd1,1)
kernel		/vmlinuz-2.6.24-24-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro quiet splash
initrd		/initrd.img-2.6.24-24-generic
quiet

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic (recovery mode)
root		(hd1,1)
kernel		/vmlinuz-2.6.24-24-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro single
initrd		/initrd.img-2.6.24-24-generic

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-23-generic
root		(hd1,1)
kernel		/vmlinuz-2.6.24-23-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro quiet splash
initrd		/initrd.img-2.6.24-23-generic
quiet

title		Ubuntu 8.04.3 LTS, kernel 2.6.24-23-generic (recovery mode)
root		(hd1,1)
kernel		/vmlinuz-2.6.24-23-generic root=UUID=0044adc9-0ba7-4876-9e3a-2a483c5ceee3 ro single
initrd		/initrd.img-2.6.24-23-generic

title		Ubuntu 8.04.3 LTS, memtest86+
root		(hd1,1)
kernel		/memtest86+.bin
quiet

### END DEBIAN AUTOMAGIC KERNELS LIST