HR22-100 Won't recognize wired PC

I cannot get the DVR to recognize my desktop PC that is connected to my home network by a LAN cable.  Both of our laptops that are connected wirelessly through my Linksys WR54TG router show up and work like a champ.  The MediaShare renderer shows up in the MP11 and is enabled on the desktop PC and it just won't show up.  I have read through dozens of threads and tried just about every throubleshooting tip out there and still no joy.  Can someone help me figure this out before it drives me crazy or gets me thrown out the house for taking so much time jacking with it?  TIA for any assistance you can provide.