It's possible the router may be a bit faulty- several others have had problems with them. before unhooking everything and taking it back, however, maybe try a simple "power cycle" of the router. Unplug it for a couple of minutes them plug it in again- this may get rid of the "brain freeze" it seems to have now.
As for my own personal use, i have had no problems at all with the D-Link brand. If you do go for an exchange the DI-624 would be a good choice.