root partition growing

[Max Freitag]

Hello,

i have kubuntu 9.10. My first harddrive (1TB) has a boot-partition and a second 
partition with dm-crypt and a lvm in it. the lvm has a root, tmp, home, .. 
partition.
I get with du and df a difference. I hade the same Problem a view weeks before. 
On the root was not enougth space left and i can't login on kde. I didn't find 
the loss space and reinstalled the system. Has anyone an idea where the space 
on my disk is gone or where i can look for it?
(kdirstat shows 5GByte used and dolphin shows 69 GByte free of 137 GByte, 50%)

sudo du --max-depth=1 -x -h /
3,3G    /usr
4,0K    /boot
12K     /tmp
0       /sys
4,0K    /selinux
8,0K    /media
1,5G    /var
4,0K    /opt
8,0K    /.config
366M    /lib
5,7M    /bin
0       /dev
528K    /.kde
20K     /mnt
200K    /srv
8,2M    /sbin
0       /proc
4,0K    /home
16K     /lost+found
2,8M    /root
5,1G    /

df -H
Dateisystem             Größe   Benut  Verf Ben% Eingehängt auf
/dev/mapper/gruppe1-root       148G    66G    75G  48% /
udev                   4,1G   295k   4,1G   1% /dev
none                   4,1G    78k   4,1G   1% /dev/shm
none                   4,1G    91k   4,1G   1% /var/run
none                   4,1G   4,1k   4,1G   1% /var/lock
none                   4,1G      0   4,1G   0% /lib/init/rw
/dev/mapper/gruppe1-tmp        50G   189M    47G   1% /tmp
/dev/sda1              5,0G   193M   4,5G   5% /boot
/dev/mapper/gruppe1-home       148G   2,5G   138G   2% /home
/dev/mapper/gruppe1-temp        99G   6,3G    88G   7% /mnt/temp
/dev/mapper/gruppe1-backup     517G    99G   393G  21% /mnt/backup
/dev/mapper/daten      1,5T   373G   1,1T  27% /mnt/daten