Okay,I've narroed down the problem. ( I've just done a complete delete and re-install of WP 3.0.1. there are no other plugin installed.) The auto-login via IP address seems to work correctly but the settings don't work correctly.
If I am at the IP address that should autologin, WP will not show any of the hidden posts. However,I am able to view hidden pages - which leads me to believe autoloin by IP is working. those pages then get hidden if I am at a differnt IP address.
I've narrowed down the problem to one setting - "Hide complete posts". The option "Hide complete posts" when set to "yes" hides all posts all the time on the client side even if I am at the set IP address that should auto login. the only time the poasts will show is if I login with user/pass. I can also get posts to show if I turn "Hide complete posts to No" (but leave "Hide post title" and"Hide Comments" to "Yes".) When I have "Hide complete posts to No" the post title/post comments show correctly when at the set IP address and display the hidden text when at a different IP address.
Hopefully I explained myself well enough. Very weird. any thoughts?