We've got two macs in the house both connected to a wireless network. Everything was working fine until last night. Now one of the macs (iMac 17") will not stay connected. If I turn airport off then on it can access internet for about 30 seconds, then stops. I thought it might have been the wireless router but I tried another one I have in the house and the problem is the same. I thought it might be a distance issue so I moved the iMac into the same room as the router and it's the same. I then connected the iMac directly to the router with an ethernet cable and the exact same problem occurs. I tried to make a new location in the Network prefs but that doesn't help either. In the meantime the other mac and my iPhone can connect to the wireless network and have no connection issues at all. And when the connection on the iMac is dropped I can access the router via my browser with no trouble at all. At this point I haven't got a clue what to try next so any advice anyone could offer would be great.