I'm hoping someone can help me with this problem. I have had my iMac since 2008 it's a 21 1/2 inch model from the same year. It's always worked just fine and is now running Mountain Lion. Last year I moved house and for some reason the blasted thing just disconnects from the WiFi constantly. When I am downloading it doesn't disconnect and when I am web browsing or using the internet directly it doesn't disconnect. After a while this problem resolved itself on it's own. I have since moved house in August and it has been fine until two weeks ago when I changed the name of my WiFi network (not any other settings just the name) now it's started again. Now when I say directly accessing the internet I mean that if I am streaming to my smart TV it will disconnect while I am watching something, it will disconnect when I log in remotely but does NOT disconnect if I am streaming directly to my iPad. This is the same across WiFi networks (e.g. streaming from work on a different network). I would think it might be Mountain Lion only when I first had this problem I was on OSX 10 and then Lion. From what I've read elsewhere this problem has been persistent across a couple years with no solid solution or update fix. Now when I changed the name of the network I had to rejoin my iMac, Apple TV, iPhone 4, iPad my gf's Mac book and her iPhone 4s and my windows laptop. Nothing else has had a problem. I have gone into the router settings and expressly permitted access to the devices I use by MAC no. and I have gone into network settings on my iMac and set it so it shouldn't disconnect without asking me for a password. Of course it ignores that completely and disconnects anyway. I hope someone can help me because I'm at wits end.