Images periodically not displaying after uploading them to the gallery

After uploading an image, mostly jpeg, for some reason about 20% of the images are broken and do not display, as well as when clicked they will not show. They are just completely unusable. I actually have to delete them, and re-upload them in order to hope that I luck out and the image shows up, sometimes 5 or more re-upload attempts. I don't have any custom code and only use a few plugins such as Bookclub Listings theme from Woothemes, and the Marketpress plugin from here, WPMU. Can you help determine why this is happening?