Hi
Sounds like dd-wrt bricked the nvram. This is a problem by not using the correct handling of the 8mb flash device which has some fancy double-use of the memory cells.
Olegs firmware has fixed this issue, i dont know about dd-wrt but the original firmware imho still has this problem. Check DD-Wrt Forums, they bricked it .
Unbricking Voids your Varanty!.
Mabe you want to send it to Asus support, i dont think they will notice you reflashed it.
Greets
Wlanman
My Stuff: WL-500g, Mapower H31x 10GB HD, Philips Webcam Vesta PRO, TerraTec Webcam PRO, USB Hub