$('').switchClass throwing error in IE8 if the switched class contains color property

hi,

I've the following css classes

		.switch-format{
			background-color: yellow;
		}
		.switch-format1{
			background-color: blue;
		}
		.switch-format2{
			color: red;
		}

Using this classes I want to do some animation on the following div

<div id="switch-class" class='switch-format' style="margin-top: 5px;">Effects - Switch</div>

Following is my jQuery code which will use switchClass to switch the classes at 5 sec interval

setTimeout(function() {
			alert('Switch 1');
			jq('#switch-class').switchClass('switch-format', 'switch-format1',
					3000);
		}, 5000);

setTimeout(function() {
			alert('Switch 2');
			jq('#switch-class').switchClass('switch-format1', 'switch-format2',
					3000)
		}, 10000);

setTimeout(function() {
			alert('Switch 3');
			jq('#switch-class').switchClass('switch-format2', 'switch-format',
					3000)
		}, 15000);

The first switch happens fine but when the second switch happens it fails in IE8, it works fine in FF3.

The error is 'Invalid Property Value'.

In IE it fails in the following line

    fx.elem.style[ fx.prop ] = fx.now + fx.unit;

with the following values

fx.prop = 'borderColor'

fx.now = NaN

fx.unit = 'px'

fx.elem.style[ fx.prop ] = ''

fx.elem is the div with id 'switch-class'

Can you help me to solve this problem