It still happens in 2.6.32-23. I forgot to say, this problem happens since I formated the HD to ext4 using Debian daily buid of 23th july and I reinstalled the system. That time, the kernel version was 2.6.32-17(I think)
Some more informations: Once it happens almost every boot, I use the GParted live (when I turn on the computer) to fix the filesystem before I try to boot the system. When I make this, the fsck does not report that error "Superblock last mount time is in the future.". It just reports, about /dev/sda5: - /dev/sda5: recovering journal - Free blocks count wrong for group #65 (8, counted=7). Fix? yes Free blocks count wrong (2181428, counted=2181427). Fix? yes The partition /dev/sda6, that contains /home, shows no errors. Is there some more information that I could give?