IE Rex X Image Problem

Hi working on a site that uses a few images here or there. All of sudden when I opend IE to test it under IE my images show up but a red x displays in the upper left hand corner.

I have seen the red X before if the image could not load or was not found, but why would this be happening if I can see the image, it has been found yet there is still a red X over the images?

Thanks.

clear your cache

nope, still comes up with this dreaded red x over one of the images.
I should of mentioned this image is a PNG 24 image and I am using a PNG transparency fix but that was a long time ago that I implemented this PNG fix and everything was working fine this morning. So I am kind of confused why this is happening. Also I am running IE8 beta... but IETester shows the image with the red x all the way back to IE6