Reboot issue

[alma at free-shell.net]

Dear,

I am having a "spontaneous" reboot issue and I really dunno what to  
do.. here is which message I get from logs .. any hints what it might  
be ??

Apr 3 06:50:44 hope kernel: Trying to mount root from ufs:/dev/ad0s1a
Apr 3 06:50:44 hope kernel: WARNING: / was not properly dismounted
Apr 3 06:50:44 hope savecore: reboot after panic: page fault
Apr 3 06:50:44 hope savecore: writing core to vmcore.3

Thank you in advance