FreeBSD 9.0 unexpected change of static route

[Krzysztof Barcikowski]

Hi,

After upgrade from FreeBSD 8.1 to FreeBSD 9.0-release (amd64) I've 
observed an unexpected behavior.
 From time to time, the static route's gateway I have defined in my 
rc.conf changes to random IP address.

In rc.conf I have:

static_routes="spp"
route_spp="-net 10.0.0.0/16 10.250.0.2"

it results with:

#netstat -nr | grep "10.0.0.0"
10.0.0.0/16        10.250.0.2         UGS         2 373253416    lan

which is OK, but after two days the route changed to:

#netstat -nr | grep "10.0.0.0"
10.0.0.0/16        213.199.225.14     UGS       455 2058321449    lan

The changed gateway address is different each time, beside that I've 
noticed one or  two cases when the default route changed.
(changes gateway IP addressess are DNS ip's, popular sites ip's, but not 
only).

No routing software is running, I have the same configuration as on 
FreeBSD 8.1 (which was OK for over a year).

I tried to log all the "route -n monitor" output but no events are 
visible at the time when the static route is changed.

Do you have any idea how can I track down what's happening, or what 
could change the routing table entry?
Perhaps I'm not aware of differences between FreeBSD 8.1 and 9.0.
Thank you for your help.

Kind regards!
Krzysiek Barcikowski