fox | technical difficulties

Any of the Mac users out there (or PC users, for all I know) organizing your photographs with Picasa? I've been sorting things over there for ages, and when I first fired it up it found every .jpg file on my computer, which, fine; and now I've got them all in one "pictures" folder, also fine, and several sub-folders, also fine; but each of the sub-folders has sub-sub-folders, and on one of these they don't show up. That is, folder A has sub-folders and some loose files in it; and folder B ditto; and folder C ditto; and folder D has sub-folders and no loose files, as it happens. And folders B, C, and D, I can see all the sub-folders; and folders B and C, if I select them, it shows me the loose files in the display window and the sub-folders over in the list window on the left, and folder D, if I select that, it doesn't know what to show me in the display window, but it shows me the sub-folders on the left no problem. But folder A, if I select it, it shows me the loose files, but I can't get it to show me the sub-folders. There's not even a little toggley triangle where I can have it flip down and show me the levels contained in the folder or anything. It's as if it thinks A is a terminal node and has no sub-folders, which is completely not true.

I've tried closing and opening the program, and I've tried moving the sub-folders out into the world, to be sisters with folder A instead of daughters of it, but nothing can make them appear. There's nothing goofy about their security settings. I'm stumped! (I guess restarting my computer is the next option. Maybe I'll try that.)

[ETA: Turns out changing the name of one file in the folder and then changing it back again makes the folder magically appear. Who knew?]