Here's one for Raymond Chen, since he likes to dig into these things.
Why the hell is the “continue from current slide” button in PowerPoint so darn small and unreachable?
Many a times have I seen the poor presenter struggling to put the cursor directly above the hellish icon to the lower left only to click a different icon by mistake, and repeatedly trying to use the darn laptop touchpad to navigate back to the icon. It looks bad, it feels bad. it is bad. Sure, it has a shortcut key (Shift+F5) but some people just rather use the mouse. Why make it so damn hard?