XP access to Lan 2k pc Shared Files

Have 3 computers Networked,(dsl,hub,+switch) 1-Me., 1-2000, 1-xp. Problem is, Me, and 2000 can access each others files, but not the XP. The 2000, recognizes the xp, but cannot access, all Clients,Services Protocols,+ Permissions, have been set. Have special names and my own Workgroup name, and Xp will not see the Workgroup. Worst of all is that it worked in the past, and with no changes, does not work now after, Networking and Tools, uninstalled and reinstalled.