WordPress adds extra <p> tags and its screwing up my design

I have:

<div id="slogan-wrapper">
<div id="slogan">
<h1>Customize any way you want it...</h1>
With Ontario's most <strong>advanced</strong> apparel and trophy design studio, you get a <strong>perfect</strong> design, every time.
</div><!-- slogan -->
</div><!-- slogan-wrapper -->

which produces:

<div id="slogan-wrapper">
<div id="slogan">
<h1>Customize any way you want it…</h1>
<p>With Ontario’s most <strong>advanced</strong> apparel and trophy design studio, you get a <strong>perfect</strong> design, every time.</div>
<p><!-- slogan --></div>
<p><!-- slogan-wrapper -->

And no matter how I change the whitespace when editing in ‘HTML’, WordPress always seems to find a way to screw it up and add extra <p> tags