I solved my own problem. After much experimenting I found that the download worked if the file name of the image to be downloaded is EXACTLY 32 characters in length, as opposed to UP TO 32 characters as the owner's manual states. I made the length of the names of 2 images 32 characters long, in one case counting the . between the name and the file extension as a character and for the other image not counting the . as a character. The image with the dot counted downloaded. I then removed the USB stick, took it back to my computer, removed one character from the name of the image that did not download, plugged the stick back into the USB port on the car, and the renamed image then downloaded also. Sounds as if a programmer made a slight error in writing the code for this function. I have sent an email to Lexus customer service. I wonder what kind of response I will get.