You can download a lot of nasty stuff from torrent sites depending what you are sharing. If programs, you have a 99.9% chance of being infected.
Have you run a virus and spyware scan? If you did it from safe mode and it was all clean, try the online scanner at
www.trendmicro.com, which is free.
You might want to run Spybot as well, after you update it and immunize it, if you are not doing so already.
It would be a good idea to read your manual for that router about encryption, not broadcasting your SSID, etc.
Did you make any changes to your system, programs, etc. before this became a constant thing?
What are some of the specific messages you get?