[CentOS] Unable to handle kernel paging request at virtual address

Hi,

I had centos 3.4 machine freeze up last nite with the following lines in 
the log. (no other messages)

Aug 25 04:02:11 host5 kernel: Unable to handle kernel paging request at 
virtual address 8395ac20
Aug 25 04:02:11 host5 kernel:  printing eip:
Aug 25 04:02:11 host5 kernel: c016d071
Aug 25 08:25:17 host5 syslogd 1.4.1: restart.

google produces a lot of these messages with varying reasons but all 
different error numbers (none with the number above)

does anyone know what may have caused this?

regards
tom