Strange Glitchy Colour Box (onrollover/out + loader)

Hey everyone, i have a strange problem which is hard to pin down or find other examples of out there. I have setup a gallery at (under the gallery side in the artist section)
In the artist section, if you scroll over the artists names fast and sometimes slow a graphical glitch can be seen where an glitchy block of colour pops up for a few seconds and disappears after you move your mouse. It only happens when the images being loaded have not been loaded before. I just dont know how to setup this gallery page to show the sample work without getting glitches. I am using a simple on mouse over ( show image in loader), on mouse out ( show same image) and so each name loads a different image on mouse over and mouse out.

Let me know if you get the same error. Thanks!!!