As a follow up, I found that this is caused by the "Activation follows mouse (X-Mouse)" setting, accessible via the TweakUI utility. This feature causes the focus to switch to the application over which the mouse is moved, without requiring the user to click on the application to gain focus. I'm really dependent on this type of focus, as I've been using it since I began using windowing systems back in the late 1980s. When I was using Office 2003 Pro on my Windows/2000 SP4 work station, I had X-Mouse enabled and still got tooltips for calendar entries (in fact, the Windows/2000 system is still running, and I just KVMd over to it and verified that it does indeed work there). Does anyone know how to get the tooltips to work even with the X-Mouse feature enabled? Thanks,