What does it cause that message "Fatal trap 12: page fault while in kernel mode" ?

[Basheer Faith]

Hello

I use FreeBSD-release6.0. the server gives an error on display as below and be locked about every 10 days.
Fatal trap 12: page fault while in kernel mode
...
...


The server has 1 gbyte Ram,  P3-550 Mhz, 2 CPU.
SMP is active in kernel.

What shall I do ?