I am not clear as to what is happening... So when you plug this USB 'keychain' drive or is it an external drive?

There is a folder that "Rec_Fischier" that is created upon plugging it into your PC... Then? The Original data is hidden while at the same time and new folders are created that are empty that have the same name as the original folders?

More clearer and concise information is needed... But...

Well, if I am interpreting what is happening... It seems that something is indeed 'funny.' Point one is that on XP and I believe most older systems you can not have the same folder or file names within the same directory; pretty sure this is the same with Vista and probably 7.

Now, how do you know that the original data is being hidden and not being deleted? Can you actually see the 'hidden original files'?

Have you tried online virus scanners? Many of them are free... Although some do not do anything but detect (so they can sell you their product).

Could it be a 'friend' or 'co-worker' that has done this to your "USB"?

Are you sure of the spelling?

Could it be Rec_Fichier NO S .. Fichier being French for File and Reçu being French for recieved.... thus it could be a Recieved Files Folder created by the software of the hardware your plugging in and thus a valid folder.

Regards Woody

Plug the drive in to a Linux box and look for hidden *.exec or *.bat files. If you find them, delete them. Delete the strange folders from the drive while using the Linux box. Anything you did not put on there is suspicious, although some drives apparently come with some resident formatting software that is generally hidden. If you are not sure you really want to delete anything, change the name to something obtuse.

If, when you return to the Windows box with the drive, the symptoms reappear, the issue is with something on your main system. It may or may not be a legitimate program gone awry, or it may be an unrecognised virus/trojan, whatever. Have you downloaded any freeware from France of late?