I think its a bad router. There is always going to be one out there on the shelves that someone is going to pick up without knowing...lucky you
You can try updating your firmware and seeing if that fixes it. Also update drivers on your wireless adapters. If that doesn't work, you'll just need to get a new router. There isn't much that can be done about a defective router, except returning it, that is, if you still have the receipt.
But also take into account that it could also be your wireless adapters....
Borgslayer