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Did you setup your macbook from a time machine backup of a previous mac? If so, there might be a rouge app that might be causing it.

It took me almost a month to find an old USB internet dongle app carried over from my old WhiteBook that was causing my more recent Macbook Pro make our entire home network disconnect from the internet almost every 15 minutes. It only showed up in the very bottom of the System Information report, and not in System Peferences >Users and Groups > Login Items.
 
@makinao - excellent point. That sort of stuff is why I'll typically do a "clean" install on a new computer, installing the apps I need as I need them. Shakes off the past clutter.
 
Don't get me started on MacBooks and wifi....for a company pushing wireless connection, I'm yet to own a MacBook that plays nice with a variety of wifi spots
 
Is the issue such that it shows that you are connected to Wifi however nothing loads, only until you turn off and on Wifi again, reconnect to the AP only then stuff starts to load?
I seem to be having this issue. It seems to work without difficulty on my home network (Airport Extreme 5th generation) but at work it seems like a few times an hour to every few hours I'll need to shut off the wifi and turn it back on to get things working again. A colleague of mine remarked that she's had the same issue with her MacBook. Nobody with a MacBook Air or MacBook Pro seems to have this issue. My iPad Mini never loses connectivity on the same network. It's highly suspicious for a problem with the MacBook... and mine is a (refurbished) 1st-generation MacBook that was set up fresh, with very little in the way of additional applications installed.
 
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