Intel PROSet/Wireless loses signal

When I start up my computer, I am instantly connected to the internet. A few minutes later, it loses the signal completely. If I turn the WiFi off and then on,the signal comes back. I have to do this several times an hour to stay on the internet.This problem has been occuring for about six months now, and I don't remember doing anything that could have caused this to happen. I know that it is a problem with this specific computer because when I use my desktop computer, I have no problems. The other computers in the house work fine too, so it is not the modem or router. Does anyone know what is wrong?