All my ports on my pc become blocked after a while

This is a curious thing as it's happened every time I reinstall windows. I try to forward a port on my router, or directly hook up the cable modem to the computer, and all the ports show up as being blocked by a firewall after about a week.

When running programs like Utorrent my ports always show up as being blocked by a firewall even through I have that port forwarded. I've also tried trigger ports with little to no success as well. It really makes no sense to me. There's got to be some way to see what's blocking up my ports on my computer, and then to try and fix it.

Right now I'm running windows vista 64 bit ultimate

This problem also occurred on my windows xp pro 32 bit.