There is an obvious distance problem with one of the devices and based on what you said that all the other computers are still connected I would say that the laptop must have a weak wireless chip.
How old is the laptop and what wireless band is it useing to connect , B, G , N ?
What brand and model is the laptop and what brand and model is the wireless router ?
Are all the other computers in the house connected by wire or wireless.
There are a lot of questions in my post so please answer them all.