Windows 2K, can’t get rid of image

So, your in Win2K, you want to lock the computer, so you press ctrl-alt-del to get to the options for log-off, change password, lock comp., etc. There is a background image at this screen that I used to use as my desktop background. The image has long since been deleted, I did not ever make any other copies, and I am going nuts trying to find where windows has stored this “ghost”. I feel pretty certain that it is in the registry some where, but cannot find it! It’s not the most critical matter in the world, but one which has me pulling my hair out! Any ideas would be greatly appreciated.