Image visibilty for guests using ck editor 3.3.1 and imce 6x2.0 beta3 - drupal 6.17

As the administrator I uploaded an image successfully and can see it, however guests to my site cannot. Following forum advice I enabled the upload. module and configured permissions but still cannot see the image as a guest. I then downloaded Image module and uploaded an image onto my site using this and guests can see this image. Suggestions for what I might try next would be gratefully received. Thanks