loader.gif and non-existing.jpg errors

I have tried everything, but have been unable to resolve these two log, "page not found" errors:

1) content/loader.gif
2) modules/ad_gallery/ad-gallery/non-existing.jpg

The loader.gif is in the ad_gallery/ad-gallery/ but does not show up in the display, only a red x in its place; so far, the non-existing.jpg does not appear to be causing any problems, only log errors.

Any help would be appreciated.

Thank you.