Router Running Slow?
Ever have your wireless router s-l-o-w d-o-w-n on you? Try this: Shut down the computer, printer, etc. Unplug the router. Count to 20. Plug the router back in. Start everything back up. Chances are, this will clear up the problem.
Now, put a reminder in your calendar to do this once each month. Remember: Routers need a little down time, too.