Hi, I recently purchased a used late-2009 macbook for my parents. I upgraded to mavericks (and to 4gb memory) and have been using it at my house with no issue on my wireless network for weeks. Now at my parents house they are unable to connect to their wireless network. Their network is without a password (don't get on me for that - different topic i know). So all that should be needed is clicking on the network name, but when doing that it simply says "unable to connect to network". Additionally my dad took it to his office and tried to connect to their wireless network and it does the same thing (you can see the SSID's but it won't connect) - he even had their network admin take a look to make sure he was doing it correctly (granted they are a Windows IT shop). So any ideas? my last suggestion was for him to reset PRAM. I have no idea why it works fine with my network (Cisco E4200 router) but now there seems to be two other networks/routers that it can see but simply won't connect to.