cat /var/log/kdm
cat: /var/log/kdm: No such file or directory
ecchimequa@natty:~$ cat /var/log/kdm.log

Backtrace:
0: /usr/bin/X (xorg_backtrace+0x3b) [0x80eaa9b]
1: /usr/bin/X (0x8048000+0x5faa8) [0x80a7aa8]
2: (vdso) (__kernel_rt_sigreturn+0x0) [0xb776c40c]
3: /usr/lib/xorg/modules/input/synaptics_drv.so (0xb66fc000+0xa482) [0xb6706482]
4: /usr/lib/xorg/modules/input/synaptics_drv.so (0xb66fc000+0xa702) [0xb6706702]
5: /usr/lib/xorg/modules/input/synaptics_drv.so (0xb66fc000+0xabb9) [0xb6706bb9]
6: /usr/lib/xorg/modules/input/synaptics_drv.so (0xb66fc000+0x6722) [0xb6702722]
7: /usr/bin/X (0x8048000+0x6b3bf) [0x80b33bf]
8: /usr/bin/X (0x8048000+0x12dd16) [0x8175d16]
9: (vdso) (__kernel_sigreturn+0x0) [0xb776c400]
10: /usr/bin/X (0x8048000+0x27ede) [0x806fede]
11: /usr/bin/X (0x8048000+0x1a7ec) [0x80627ec]
12: /lib/i386-linux-gnu/libc.so.6 (__libc_start_main+0xe7) [0xb747be37]
13: /usr/bin/X (0x8048000+0x1a3e1) [0x80623e1]
Segmentation fault at address (nil)

Caught signal 11 (Segmentation fault). Server aborting


x restarts it'0s this ?
/usr/lib/xorg/modules/input/synaptics_drv.so

That looks like the synaptic driver crashing, hardly anything to do with KDE...

solved i have removed some stuff like the wacom driver and the synaptic stuff now i have not X restart ,
the question was born because on this


04/02/11 02:14:13 PM localhost kdm[925] X server for display :0 terminated unexpectedly

Correct, kdm is failing to start, because it requires the X server to operate, and cannot start the X server due to a bug in X itself (namely in it's synaptic driver). I suggest making sure your system is up to date, and contacting your distributor (through their forums or mailing lists) for further assistance.