Frustratingly, I could not find a solution to the problem outlined in KB 883517, even after installing the hotfix (for me, it was available from the computer manufacturer in a file called "Windows XP Update Modules").
The problem was that Balloon Tips were disabled. To enable Balloon Tips, go to the Taskbar and Start Menu section of Tweak UI. The option took effect right away, and the "It is now safe to remove your hardware" dialog reappeared.
