and how to stop the system to make thumb.db files? MS likes to make rubbish, then people have to delete them.
You don't need 3rd party software for this, just use the Disk Cleanup utility. It's under Start -> All Programs -> Accessories -> System Tools (or Windows Key + R to bring up the Run dialog, then type in "cleanmgr.exe" and hit OK). It will take a couple minutes to scan your system, but when it's finished, one of the options in the list will be "Thumbnails". Make sure it's checked, then check or uncheck anything else you want to clean up or leave alone, then click OK. If you want to stop Windows from creating the thumbnail files in the first place, follow this link: http://www.sitepoint.com/switch-off-thumbs-db-in-windows/ Note that I believe disabling the creating of the files entirely only works on Windows versions other than Home (like Pro/Enterprise/Ultimate/etc), since I don't think Home has the Group Policy Editor application that's necessary. Doesn't hurt to try though - if your system doesn't have it, it'll tell you.
I checked C: dick cleanup. There is a option to delete all thumbnails. 1) can I delete all delete thumb.db files by deleting all thumbnails? 2) but if I delete all thumbnails? will I lost all thumbnail pictures,
I'm not exactly sure what you mean. Thumbs.db is basically a database file that stores an internal thumbnail version of each image in that folder. This is done so when you view the contents of that folder, Windows Explorer can very quickly show a preview of what the full image looks like. Without it, it would take longer to scan each photo to generate a preview thumbnail on the fly each time you browse to that folder. The Disk Cleanup application deletes all the Thumbs.db files, but does not touch the actual image files.
