IE-specific issue.

Let's say an element has an existing opacity value set in the CSS like this: filter:alpha(opacity=65);

If you try to use fadeOut, the animation will always start changing the opacity value beginning at 100, instead of its inital value of 65. This creates a "flash", as the element's opacity gets set back to 100 for a split-second before it starts to fade out.

The IE-specific fix should be that the fadeOut method (really the curCSS method) checks the element's "filters" collection to get the current opacity value and start from there, instead of defaulting to 100 (since the element won't have an opacity style set, only the alpha filter).