Samba stop after 15 minute

Hi My Samba Stop 2 or 3 time a hour

i got version Samba version 3.4.3-3.8.1-2508-SUSE-SL11.2
install on openSUSE 11.2 “Emerald” - Kernel (39).

I got two network card

My samba is configure as a share so no user are involved

i use webmin version 1.620 to patch the trouble by monitoring the samba service et restarting it

i upgrade the log level at 3 but when a check my log a got no clue what is going on
could someone help
thank you