When you say:
neither the ethernet cabled' computers or the wireless ones have the same problem.
What do you mean? That all the computers have this problem, just one wireless one..?
You could try removing and adding the network details, windows has been known to get confused. Go to control panel => network connections => right click wireless connection => properties. If your home network is there then remove it. Reboot and go to the same place again, but this time choose "new" and enter the relevant details.