My dad who is also connected to the router on a different comp has SEVEN IE's open.
Definitely. You and your dad (and any else online via the same router) are pumping data down the same internet pipe.
If the combined traffic saturates either the bandwidth of the internet connection, or the internal processing bandwidth of your router (many routers for the home market really don't have the internal processing power to handle the huge highspeed datastreams we need today), then something has to give = packet loss.
Tell your dad to stop browsing for internet pr0n while you are online. That might fix it:D
Out of bats, Out of bots, Out of torps - Down to harsh language...