Blink bbcode conflicts with quick reply

I noticed that some topics on my board did not have the quick reply button. After some troubleshooting I managed to figure out what was going on...
One of my members had a text in his signature which was using blink bbcode..
In the same topic, all pages that do not have any blinking text have the quick reply button normally.
It does not matter how many times the blink bbcode is used in a page - one time is enough...
The HTML replacement I use is the following:

<script type="text/javascript">

            <!--

            function doBlink() {

            var b = document.all.tags("BLINK")

            for ( i=0; i < b.length; i++)b[i].style.visibility = (b[i].style.visibility

            == "" )? "hidden" : "" }

            function startBlink() {

            if (document.all)setInterval("doBlink()",800)}

            window.onload = startBlink;

            //-->

            </script>

    <blink>{TEXT}</blink>

If I try to use

<span style="text-decoration: blink;">{TEXT}</span>

instead, the quick reply appears normally, BUT this bbcode won't work in IE... Not good
I'm hoping that you will come up with a solution...