Are you sure you bought a switch and not a router? Plugging a switch into your network will not cause anything to fail (please post a link to the switch you bought).
If you bought a switch with a built in router then it could be causing interference with the other router on your network thus causing all of your devices to be confused as to where to send data.
If you bought a switch with a built in router then it could be causing interference with the other router on your network thus causing all of your devices to be confused as to where to send data.