Thanks, I checked, remote administation is disabled. I'm using MAC address filtering & WPA2 with a strong encryption key, so I doubt anyone is getting in from outside the network, and I keep the login username & password in my head, but maybe I'll change them again just to be sure.
I'll wait & see if it happens again. If it does, I'll try to return it. Luckily, I bought it at a locally owned shop, they will be accomodating.