Etch changing ip number

Hi, i have a recently installed etch web-server which is making me crasy because it changes it's ip address by itself. I have, since it is a server, configured it via /etc/network/interfaces to have a static ip address, it's just a typical post installation thing to do on a server right? I do some web development via Zendstudio and ssh directly on the server and it just so happens that all the sudden i loose connection and when i do an ifconfig on my server i see that the server has changed its ip address to one that's in my dhcp range. I do an /etc/init.d/networking restart and i'm back on my static address for some time.

Here's my config:

auto eth0
iface eth0 inet static
address 192.168.1.245
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1

Anyone who has had this problem?

Regards Fredrik