dowloading pictures

Hey guys; I use to download a lot of pictures of the Net. As I have yet no CD Rewritable I put some on floppy. Let's say I put picture A on the floppy. After putting it on I delete the picture so it goes to Trash. After the work is done,I empty Trash. I go surfing again,with the necessary downloads. I open my user home directory,I open my floppy and kdf. Then I click "show thumbnails". Weird thing happens as often the old picture A is shown as a thumbnail,but if you open it it's the newly downloaded picture you see. How can a deleted picture reappear again as thumbnail? Is this a bug or do I have a hacker controlling my Trash? Greetings Jean-Paul