We are currently in the process of installing iMacs for a client to replace their aging PC workstations. One of the iMacs we installed has recently started having a problem with the keyboard and mouse -- whenever the user's iPhone is plugged into the computer, the keyboard and mouse become unresponsive and the computer has to be restarted. We've tried swapping out the keyboard and mouse with those from another iMac and the same problem occurs (and the original keyboard and mouse work fine on the other iMac). Any idea what could be causing this and how to fix it? Thanks in advance.