At least my my WRT54G routers around here, most start misbehaving a couple of times a year and just using the factory reset button on the back and resetting the parameters fixes it up. I haven't found that any amount of futzing with the menus works, and none of the parameters change.

My oldest WRT54G actually never needs this, it's been on for years. It's all the newer than V1 that occasionally fail.