i dont know if this will work for you but yesterday i managed to change my light from yellow to green but i waited till this morning to check it had still worked as usualy when i shut down and restart it goes back to yellow but it hasn't if your running xp try this -
GO INTO ADD/REMOVE PROGRAMS AND CLICK ON
ADD/REMOVE WINDOWS COMPONENTS THEN
CLICK ON NETWORKING SERVICES AND PRESS DETAILS AND IF PEER TO PEER HAS NOT GOT A TICK ON IT TICK IT AND SAME WITH UPNP THEN CLICK NEXT
YOU SHOULD GET A GREEN LIGHT ON STATUS ON BITCOMET AND UTORRENT I TRIED IT ON BOTH WERE I HAD THE SAME PROBLEM AND IT HAS WORKED
I HOPE IT WORKS FOR YOU IT LIKE IT HAS FOR ME PLEASE LET ME KNOW IF IT DOES SO THAT I CAN LET A COUPLE OF OTHER SITES KNOW WHO ARE HAVING THE SAME PROBLEM
TRY (PORTFORWARD.COM) FOR CONFIGUREING YOUR ROUTER it has a very wide range of routers on there
ALSO PLEASE READ BELOW
i found out something today if you have a NVIDIA ethernet port with built in fire wall and anti hacking turn it off i turned mine on today by accident and straight away it blocked bitcomet and the yellow light came straight on i had to turn it off by using (nvidia ,network access manager)web based interface to turn it back green the fire wall on its own works fine with bitcomet but the anti hacking facility blocks it and keeps it yellow