Vista fails to recognize ext HDD?

HP Laptop, hooked to a wireless secured network. The laptop was connected to the ext hdd before it was wiped and redone. Now I cant get the laptop to recognize the ext hdd. I have 3 other computers (2 running 7 and 1 running Vista) that are still connected to the net hdd. I've already check the network sharing settings, and they are all set to share. the Ext Hdd is a WD My Book Live 1TB.