network manager probably ignores static address

[lyon]

Binary package hint: network-manager

I'm using DHCP mostly on my eth0 card, but I sometimes need to set up a static address. If I set up my own static address in Ubuntu's network settings dialogue, my eth0 interface reverts back to DHCP address in a few seconds or to a private 169.254.* address if no DHCP server is found. This is annoying, because I can't switch to private address whenever I need to :(

Hint: If I "disable" the network in nm-applet and after that I set the address manually, it stays, but this is not how I would expect it to work.