Problems streaming media from pc to xbox.?

Hi, my xbox and my pc DO recognize eachother. My 360 shows my pc and my 360 is allowed media sharing in windows media player. At first my music files and video files played just fine on my 360, but after I cleared my library to start from scratch and reorganize my music my 360 now shows no music files(that is of course AFTER I put them back in WMP). I can still stream a videos that I happened to NOT delete, but none of my music plays on my 360. What can I do to fix this? I have Windows XP Home Edition 2002 Service Pack 2, and I have both my 360 and PC connected into my modem(which has multiple ports thus I don't require a router). I have downloaded WMP 11 and as I stated before it was working initially. Please help.