I left my PC on last night to run a viruscan. When I checked it this morning I had no viruses but I noticed that something was downloading data onto my PC from the internet. I determined this by checking a program I have called DU Meter which monitors the flow of network traffic across my ethernet connection. Other than Norton Antivirus, no other programs were running and as far as I could tell there were no programs running that would be downloading data from the net.

My question is, how can I determine what was causing this data transmission across my internet connection?

Thanks,
Ben

Well if Norton Antivirus was running it was possibly doing a live update. To find out which program is doing something you could press ctrl + alt + del and bring up the task manager. Firstly, look at which process has the highest memory and cpu usage. For example, I saw a computer once that had the process worm.exe using up the memory... this was a pretty big give away. If nothing sets off any alarm bells then you can try shutting down programs that are running until shutting down one of them eventually stops the data flow. If this still doesn't work then you can shut down processes that are still running using the end process button in your task manager. Please note that this has a tendency to make you computer unstable and will most probably crash eventually so don't do this while you have anything unsaved or important running. In fact if you can avoid doing this completely I would.

Alternately you can download a packet sniffer and take a look at the data being transferred across your network. You may be able to decipher which program is sending the most packets from there.