[Ntop] Box stop answer after a while

[Fabricio Lima]

I'm using this ntop described bellow, but after a small time, the ntop box 
stops responding to Ping (my SSH connection is dropped also).

If I stop the ntop server, the box runs quite fine.
The server it is a Pentium III Xeon with 1GB RAM.

FreeBSD 5.4-RELEASE + ntop-3.1_1 + libpcap version 0.8.3

Started as.... /usr/local/bin/ntop -d -L --set-pcap-nonblocking --skip-
version-check -i lan1 -w 3000 -W 0 -a /var/log/ntop.access.log -u nobody 

/etc/sysctl.conf

security.bsd.see_other_uids=0
net.inet.ip.check_interface=1 # protection against spoof ip packets
net.inet.ip.random_id=1
net.inet.ip.fastforwarding=1
net.inet.icmp.maskrepl=0
net.inet.udp.blackhole=1
net.inet.tcp.blackhole=2  # blackhole pings, traceroutes, etc.
net.inet.tcp.recvspace=65535
net.inet.tcp.sendspace=65535
net.inet.tcp.rfc3042=1 # Enhancing TCP's Loss Recovery Using Limited Transmit
net.inet.tcp.rfc3390=1 # Increasing TCP's Initial Window
net.inet.tcp.sack.enable=1
net.inet.tcp.keepidle=300000
net.inet.tcp.keepintvl=150
kern.fallback_elf_brand=3
kern.polling.enable=1 # network interface pooling instead interrupt request
kern.ipc.shm_use_phys=1 # kernel to lock shared memory into RAM and prevent 
it from being paged out to swap
kern.ipc.maxsockbuf=1048576 # Buffers de socket para novas conexoes