Thumbs.db in Windows 7
I was using a Windows 7 Professional Edition machine to browse a network share on a Windows XP Home Edition netbook. The share contained two JPEG image files which I had put there. Seconds after browsing the network share, a
thumbs.db file appeared beside the two image file.
I knew that Windows XP machine could have not created the file, since I had disabled thumbnail caching on that machine. To be certain, I checked the file’s creation time and ran
cacls.exe to dump its NTFS permissions. As I expected, the file creation time was almost the same as that of my browsing time and the Guest account had full access permission. (In Windows XP Home Edition, any file created on a network share by a user on a remote computer is owned by Guest account. That is not always the case with Windows XP Professional Edition.)
Microsoft has confirmed this behavior and explained how to disable it. Please see: Renaming a network folder in Windows 7 Explorer fails with “the action can’t be completed…” (21 November 2011)