My MacBook Air (OS X 10.9.5) has started acting weird. Lately it doesn't allow me access to many of the major websites I use like Google and Facebook but smaller e.g. local newspaper sites still work (it can work fine in the morning and then act up in the evening). I don't know what the problem is (and I'm not very good with this sort of thing). We have another Mac in the house and it works fine all the time so with it I've been trying to Google some answers (feels ironic somehow...) and have tried all the usual things like clearing cookies and cache, restarting computer, putting in new DNS (220.127.116.11; 18.104.22.168, not even sure what that is supposed to do but all hail mighty Google). I am at a loss so if anyone has any ideas that could help I would be very grateful.