I've previously downgraded to 1.03, and the problems disappeared. However, restoring settings saved from newer version does not work. But the problems we're having here do disappear.
This too makes me think that this is a firmware problem. Which brings me to another question, though I think I know the answer...
If there is nothing secret in the router firmware, maybe dlink could make it at list somewhat open source? I'm pretty sure this would allow for a lot more bug fixes and new features to be added. But I think I already know the answer to this...