Joe,
do have a wireless access point? If so make sure you have enabled encryption to prevent your neighbours from logging on and nicking your bandwidth. Maybe you have a neighbour that is in the habit of surfing and downloading prodigious ammounts of porn after midday.
I used to be a bit blase about such things until one day I came home in the middle of the day and found some theiving little git sitting in my front garden, with his laptop, logged onto my home network.
pb