crazy network problem -- sleep?

[stutiredboy]

hi,all:

	recently , we  found a problem that , some server which with FreeBSD
6.2 may stop networking after
days of services, it is so difficulty express this status, e, such as
sleep?  i can not ping this server, tracert is also
failure, and other services ,network/server seems to be down... but
while i insert the keyboard/mouse/crt in ,
everything is ok, such as a ring to call the system to wake-up... no
errors found in dmesg or /var/log/messages,
such as nothing happened...orz，our unlimit args as follow:

cputime      unlimited
filesize     unlimited
datasize     2088152 kbytes
stacksize    65536 kbytes
coredumpsize unlimited
memoryuse    unlimited
vmemoryuse   unlimited
descriptors  655000
memorylocked unlimited
maxproc      5547
sbsize       unlimited

plz give me some suggestion to trace the problem or solve it . thanks a
lot !

Best wishes !