I have to turn off and on Home Sharing for things to work, why?

I have three AT2 (latest firmware) in the house, all on wifi through an airport extreme. I have a windows 7 box in the basement hardwired to the airport extreme as the server. Everything is fine until i either restart the windows 7 box or restart itunes. When ever i have to do either, i have to goto the at2 and go into home sharing setting and turn it off and then back on for my library to come up. It works almost everytime but its a little annoying considering it has to be done on all three at2. I dont have a problem with it as much as my kids who are too young to firgure it out. But once i do turn it off and then back on, everything is fine until the next time i either restart the windows 7 box or restart itunes. Any ideas?