Started not too long ago and only affects my macbook, not the desktop connected to the router or the gateway notebook with wifi access. Basically internet starts getting really slow until it barely works. I found that by turning off airport and turning it back on a few seconds later fixes it for anywhere between a few minutes and a few hours. I telecommute so this is a big problem for me. I doubt it's related to the router but I upgraded the firmware just in case, it's a Linksys WRT54gl running Tomato firmware. Same problem. Anybody have any idea what could be causing this?