Handy hint for Magic Mousers. A few people in work (including me) have a Magic Mouse connected to their Mac. Over the last few weeks, as batteries have been swapped, they all started losing connection constantly and became pretty much useless. One mouse, ok it's dying. Two mice, coincidence. A whole load of mice in the same office within a week or so... something's up.
So the new stock of batteries we had were Duracells, as batteries got changed, mice lost connections. Apparently Duracell AA batteries are slightly different in dimensions to other AA batteries, enough to lose connection in the Magic Mouse. Energizers in them all now, and they're fine.