Wireless ad hoc network won't connect automatically

I have a wireless network connecting 3 computers. 1 is running W7 home premium, 1 XP home and one XP pro. The W7 machine detects the network but will not connect automatically. The tick boxes on the Connections tab on the network properties box are not present while running as a limited user or as Administrator. The W7 machine has recently been upgraded from Vista but had the same problem with Vista. The XP machines connect automatically but the XP home maching connects as an unsecured network if it is started up first (the network is WEP secured). If the XP pro or W7 machines are connected first the XP home machine connects correctly to the secure network. Internet connection sharing is normally enabled through the XP home machine
Any suggestions - particularly for the automatic connection issue?

This website is not affiliated, owned, or endorsed by Microsoft Corporation. It is a member of the Microsoft Partner Program.