Wow, looked through all these suggestions... none are helpful. I agree with the majority here, FIX IT! I never have this problem on a Mac. Please, if someone finds a real solution, I'm ready to hear it!!
I love it. I detail exactly what's causing the problem AND how to avoid it in the post before this, and you don't even bother to read it :P
As an addendum to what I said earlier, my personal speculation is this only happens the FIRST time windows explorer has to load the thumbnails in question, because it hasn't got them cached in thumbs.db yet. Trick is, it seems to store them on a folder-by-folder
basis, and even then only when the preview actually shows up on screen.
Say it's your music library, you've never really used anything but player software to go through the contents. You're going through and trying to clean it up. Any of the following things will then lock the folder:
You're set to an icon size that has previews, and scroll down to where the folder is visible for the first time.
You're set to a small icon size and click on the folder, bringing up the preview in the details pane.
You've already brought up the top level folder preview somehow previously, but not the subfolder. You then enter the folder, and one of the above happens with the subfolder. (each folder has its own thumbs.db!)
You've already triggered the subfolder preview previously, but haven't been inside it. You go into the subfolder, and trigger one of the above with one or more of the files. Or the latter case, but with the preview pane instead of the details pane.
In short, there are three ways to avoid the issue:
Have previously browsed the folders and triggered their preview thumbnails, so it doesn't have to load the files to get them.
Disable preview thumbnails entirely, which is harder to undo then the last option:
Turn off *all* options that can generate a preview thumbnail: the details pane, the preview pane, and setting your 'view' size to 'small icons', 'list', or 'details'.
You *must* do all three, or one of the others will trigger the problem again.