This problem occurs in any 1.3.x and and 1.4.x release.

The black pixel problem is a bug in the IE filters / layout system which we cannot fix, but at least we can work around it when the elements should be fully opaque.

The solution is to not apply the "alpha(opacity=n)" filter when the opacity value is "1".

Code

// Set the alpha filter to set the opacity
var opacity = jQuery.isNaN(value) ?
	"" :
	"alpha(opacity=" + value * 100 + ")",
	filter = style.filter || "";

becomes (jQuery v1.4.4rc2 line 5269)

// Set the alpha filter to set the opacity
var opacity = jQuery.isNaN(value) || parseInt( value, 10 ) + "" === "1" ?
	"" :
	"alpha(opacity=" + value * 100 + ")",
	filter = style.filter || "";

See attachment for test case and solution.