Static Ip address changed on reboot

Hello all
I have a problem setting up a static Ip address for my connection.
When i set it the first time it seems to be working fine, but every time i
reboot the pc then all the information is lost and Vista moves back to an
automatic address (if i tick the Use this IP address, the one i input is not
there anymore). this happens all the time i reboot.

How can i solve this issue? many thanks