Thanks flashpipe1 for the advice but its still not working.

I have a rectangle over the image (no alpha) and have made that my target area - so the size is constant. It still does the same thing.

I can't just make a large image in one frame and a small one in the next becuase the image needs to visibly grow from its small state to its large state when the mouse is over it, not just become large.

Your third idea might work, but I have no idea how to go about doing it.

Any suggestions?