Has anyone seen this bug?

I have a sidebar with a ul nav background image for the hover state, floated right, looks great in all browsers.

Then...I added another div underneath it for ad space. inside, there's an anchored image. That image tucks underneath the background image of the nav, but only in IE7 (i abandoned trying to please ie6).

So I took it out of the sidebar, played with float, display,height hacks, but nothing works I can declare a large top margin with some more top padding do get it to clear but it breaks the design. i even tried creating a div called clear and put a top margin there. so it displays with this huge gap in chrome, FF, safari but this tiny space between in IE. i even tried creating a div called clear and put a top margin there.

I have spent hours trying to find someone with the same problem but to no avail. Any suggestions?

Here's a code snippet:

<div id="leftsidebar">
    <div id="leftnav">
        <ul class="slidenav" id="sidenav">
            <li id="overview" class="inactive">
                <a href="expat.html">expat lifestyle</a>
            </li>
            <li id="tips" class="inactive">
                <a href="traveltips.html">travel tips</a>
            </li>
            <li id="bts" class="inactive">
                <a href="bts-mrt.html">bts/mrt</a>
            </li>
            <li id="bus" class="inactive">
                <a href="bus.html">bus system</a>
            </li>
            <li id="van" class="inactive">
                <a href="taxi.html">vans/taxis</a>
            </li>
            <li id="boat" class="inactive">
                <a href="klong.html">boats/klong</a>
            </li>
            <li id="boat" class="inactive">
                <a href="klong.html">boats/klong</a>
            </li>
            <li id="tuk" class="inactive">
                <a href="tuk.html">tuk-tuks</a>
            </li>
            <li id="train" class="inactive">
                <a href="train.html">trains</a>
            </li>
            <li id="airport" class="inactive">
                <a href="airport.html">int'l airport</a>
            </li>
            <li id="dangers" class="inactive">
                <a href="dangers.html">dangers</a>
            </li>
            <li id="fun" class="inactive">
                <a href="fun.html">fun places</a>
            </li>
            <li id="shopping" class="inactive">
                <a href="shopping.html">shopping</a>
            </li>
        </ul>
    </div>
</div>
<div id="store">
    <a href="astore.amazon.com/ten044-20"; title="Shop WIB store">
        <img src="images/WIBstore.png" height="70" width="200" border="none"/>
    </a>
</div>

the corresponding CSS:

#leftsidebar {
  float:right;
  width: 210px;
  margin: 40px 0 0 0;
  padding: 0;
  height:1%;
}
#store {
  margin: 20px 0px 0 0px;
  padding: 0 10px 0 0;
  float: right;
  height: 1%;
  display: inline;
}

And an image: