Vista - Networking issues with WMP 11

I have a computer that runs Vista Business that I just use it for file sharing and basically as a network drive. I can access it from my laptop as network drives and through remote desktop at all times, but when I go to access it from my xbox 360 it doesn't show up most times. It used to show up and work all the time and something lately has changed (maybe a update). I have WMP set up to share to the xbox. To get the files to show up on my xbox again I have to either restart the computer or disable the network adapter and restart it and then I'm able to see it again. But if I leave it sit till say 6 hours later it won't find that computer again. I can access my laptop that runs Ultimate all time, so this leads me to believe its a networking issue with that computer. Any ideas on how to fix it?

Am I the only one that experiences this problem?