There are a couple of things that can cause a user to look busy all the time — and one of them is not setting up the free-time look-up at all, but simply leaving the defaults in place. Has the user updated the defaults? Also, are any of the times “invalid,” that is, do they make sense? I have seen where the times get translated in local time to something like 6:00 PM-2:00 AM, and Notes does NOT like time periods that go over midnight. Also, be sure to check Saturday and Sunday — even if the user isn’t in those days, if the times don’t make sense or go over midnight, they seem to cause trouble.
Also, in Notes 6.5.x, I’ve noticed that “link” error messages often turn out to be related not to actual links, but to corruption of either the bookmarks (close Notes, delete Bookmark.nsf and let them recreate on startup) or the workspace (I know we aren’t supposed to be using it, but it still happens). If it’s the workspace, go to it (it’s in the “databases” folder on the icon bar), remove the icon for the mailfile, compact the workspace, close Notes, reopen, and go back into the mailfile by the bookmarks. It’s amazing how many things you can fix by simply recreating the bookmarks or compacting the workspace.