Stop Windows 7 Reassigning (and Half-hiding) Folders

Stop Windows 7 assigning my folders to its own special ones

This is a year-old Windows 7 Pro PC that gets very heavy home office use. Just yesterday I noticed that 2 top-level folders I created long ago no longer appear in the Explorer view of folders under C:.

In each case, if I explicitly enter the folder's path in the address bar (or the Run dialog), the folder content displays, but the address bar reads, for example, Computer - OS (C) - My Pictures. (The title bar shows the path, but the address bar is beating its own drum.) Another folder has now suddenly been declared My Music. And while these folders do contain lots of pictures and music, respectively, they have other stuff in them too, and I don't want Windows to apply its heavy-handed classifications. Strangest thing is, I'm certain the My Pictures and My Music folders were located elsewhere until yesterday.

If I go up one level from either folder (to C), the folder's name & icon are not shown in the list of other top-level folders. That is, I can't cursor down to it and hit Enter to open, as I can with dozens of others.

I've never used, nor liked being cajoled into using, Microsoft's array of "My XXXX" folders, nor am I partial to the recently birthed "libraries" concept. I have my own carefully designed folder hierarchy, and must work in it at great speed, so short paths and quick keyboard access are critical. I deliberately name certain folders toward the top of the alphabet, so scrolling down to the 'My's -- even if I were to accept these involuntary relocations

This only just started, and I can't figure out what provoked it. Is there a setting that governs this that can be disabled? If it's a new "feature" added in an update, I see it as inexcusably intrusive.