>I'm seeing this also, it also seems to leave incorrect arp entry
>I'm getting this on i386 so it is not port specific.

ThanX for the support!!!

>did'nt help a bit. (Hmhm, actually it wasnt executable, so it might work)

chmod 555 ip-down
chown root:wheel ip-down

I'll try it in my setup, now it's like:
#!/bin/sh
#ip-down
#$1 interface-name
#$2 tty-device
#$3 speed
#$4 local-IP-address
#$5 remote-IP-address

echo $2 > /etc/ppp/tty.$1
clienttty=`sed -n -e "/\/dev\// s/\/dev\/:*//p" < /etc/ppp/tty.$1`
echo `who | grep ${clienttty}` " on" $5 "out at : " `date` >> /var/log/ppp

ifconfig $1 down
sleep 2
route delete $5
route delete $5
arp -d $5

exit 0

Let you hear later on in the day how it's working,
~n