Recently I ran across a Windows XP tip that explains something that's been quietly bothering me for a while. I've written before, that when I'm viewing files in Windows Explorer, I like to see all the details. So my default folder views are set to show lists of files with all the details.
As a refresher, to change your folder options, set a folder with the view options you like, then choose Tools|Folder Options and then click the View tab. Click Apply to All Folders to apply the view you are using for the current folder to all folders. (You also can access the Folder Options from Control Panel, if you prefer.)
The trouble is that on some folders, it seemed like the setting didn't stick. Apparently, "all folders" doesn't really mean every single folder on your system. When you switch a folder to Thumbnails view, Windows adds a little file called Thumbs.db. I've noticed this file before in file listings and wondered what it was. As it turns out, it's the thumbnail cache. The idea is that by creating this little file, the next time you go to the folder, Windows can redraw your thumbnails more quickly because information about them has been stored in this little file.
So the reason my Apply to All Folders setting didn't work on some folders is because those folders had the Thumbs.db file in there. When Windows sees that file, it assumes you want to look at the files in Thumbnails view.
On folders that have a lot of pictures in them, I do switch to Thumbnails view to check them out sometimes. But usually I switch back to details view, to speed things up. Later I'd go back and it would seem like Windows didn't remember that I switched back to Details view. There was Thumbnails view again. (I hate mysteries like that.)
Anyway, to make Windows forget about thumbnails, I just needed to change one of the folder options. Choose Tools| Folder Options and click View. Now click to add the checkmark next to the Do not cache thumbnails option. Then click Ok.
You also can freely delete the Thumbs.db files without hurting anything. The only thing is that if you do switch to Thumbnails view, it may take slightly longer for the pictures to redraw.