Help With Media Sharing Problem PLEASE!!!

I am trying to set up media sharing from my dell xps m1530 running windows
vista with windows media player 11 to my xbox 360. In following the
directions provided in the help files you open media player, click the
library drop down menu, then click media sharing. to start media sharing you
check the check box next to "share my media". at this point I click ok, and
then nothing happens, the media sharing window remains open and the ok
button becomes grayed out but then nothing. the next step says there should
be another menu where selection of allowable devices could take place but I
never see this option. I had media sharing setup with my older laptop that
was also running WMP 11 so I've done this before with no problems. I have
tried deleting the DRM files to no avail. I have also reset the services
that I was informed were needed to share media, including SSDP Discovery,
UPnP device host and the Windows Media Player Network sharing service. I
feel confident it is a localized problem and not a network issue. I tried
the setup on my sisters HP laptop running Vista and WMP 11 and it worked
right away. any insights would be greatly appreciated.