Behavior 1: Verify that the WMP playlist is clear of all songs. Turn on the "Shuffle" and "Repeat" features. Double-click on a music track in the Library. Click the "Next" button (double right angle brackets). A random song from any track in the Library is randomly chosen and played. When observing the Playlist (clicking the "Play" tab), the entire contents of the Library appears in the Playlist. Behavior 2: Verify that the WMP playlist is clear of all songs. Turn on the "Shuffle" and "Repeat" features. Double-click on a music track in the Library. Click the "Next" button (double right angle brackets). The button visually depresses like it has registered the click, but nothing happens. Absolutely nothing. Moreover, the "Previous" button is grayed out. When observing the Playlist, only the one song that was double-clicked appears in the Playlist. What causes Behavior 2? I cannot correlate any specific action I've taken with Behavior 2, and Behavior 1 has been the case as long as I can remember, all the way back to Windows XP. Even earlier during my usage of Windows 8, I recall Behavior 1 working correctly. But suddenly, inexplicably, without changing any settings in WMP, Behavior 2 kicked in, and persists after reboots. I've tried sfc /scannow in an administrator prompt. All system files are in order. I've downloaded all Windows Updates and driver updates. I've attempted to alter WMP options and playback settings to no avail. So... what is causing Behavior 2? Is this an intended, valid behavior, or is something malfunctioning? How would I know what that "something" is? How would I go about fixing it without just reinstalling Windows 8 fresh?