Problems with Internet on 5.0.1

[Capricorny]

I could ping both ways, so there was no general DNS lookup failure involved. And there was no general failure in the router, as both DSL 3.0.1 (from USB-stick) and Mandriva2006 (from disk) on the same machine, with no network switching, worked perfectly. It happened at last boot also on this machine I am using right now (an Asus A3Hf, with the same Zyxel router), so there must be some underlying problems.