Vista - Hidden contact list

Been having a small problem with WLM, and I have my friends and family in one
group, and others in another, fine, no problem there.........
The problem is that when I click on the tab to hide the members of that
group, eg friends and family, anyone who is online should remain visible,
should they not?
Well, they used to......... but now when the list is hidden, I am not
getting any alerts as to when one of my contacts goes on line, so I have to
keep the list visible as to see who is active, and who is not......... Have I
got a registry key issue?
or is it "Broke" and needs to be De/Re -installed?

Thanks for any help in advance........
Nick.........