ports only work for approx 1 day

[edpelo]

i open and forward a port to uTorrent. it works fine including the port forward test, etc. i'm all green. great speeds. then, within about 24 hours, the port is no good. i get the yellow warning, slow speeds, and if i run the test i get the not forwarded correctly message. the only way i can get it to work again is to change to a different port... and then, again, it only works for about 24 hours. is this an oversight on my end, or my ISP screwing with me (I have standard Qwest DSL btw).

thanks