Sometimes (maybe one case in 3), when I unplug the wireless mouse receiver on my Sony VGN-CS215J laptop, there is no "da-doomp" sound, even after a minute or two. And if I plug the receiver back in there is no corresponding "du-dump" sound and the mouse is still (immediately) "live". This can happen when the activity light is out and there's nothing obviously going on -- it's not simply that the box is too busy. Other times one gets the expected behavior (and usually I get the correct behavior if I plug the receiver back in a few seconds and then unplug it after a "failure").
The reason this is significant is that if I get no "da-doomp" then the laptop will not sleep properly -- it will go to sleep initially, but then reawaken a few minutes later inside my laptop case and proceed to run the battery down (and no doubt overheat the unit).
Added: The problem went away after I had to reload the system. Likely it was caused by an excess of (pre-installed) "junk" cluttering up the interrupt system.