Server periodically rebooted

[Rashid N. Achilov]

FreeBSD master.askd.ru 6.3-STABLE FreeBSD 6.3-STABLE #21: Mon Feb 18 13:05:59 
NOVT 2008     root at master.askd.ru:/usr/obj/usr/src/sys/Master  i386

Intel DQ965GF, Core Duo
Jun 19 10:34:50 master kernel: sio4: <NetMos NM9835 Dual UART and 1284 Printer 
port> on puc0
Jun 19 10:34:50 master kernel: sio4: type 16550A

Periodically, server silently rebooted. That occassion will be only when exist 
active user, works on dial-up connection. NetMos installed, but not used, 
used motherboard COM port, used pppd with simply PAP auth. How to exclude 
these reboots?
-- 
   With Best Regards.
   Rashid N. Achilov (RNA1-RIPE), Web: http://www.askd.ru/~shelton
   OOO "ACK" telecommunications administrator, e-mail: achilov-rn [at] askd.ru
   PGP: 83 CD E2 A7 37 4A D5 81 D6 D6 52 BF C9 2F 85 AF 97 BE CB 0A