CSS width fills out in IE8 Compatibility mode, works as it should in normal mode

Question

I am trying to create a border around an image on the page, and the border works fine in IE8 Normal mode, but fills to 100% of the outer div in IE8 compatibility mode, my css is the following:

.page-layout .page-header .page-image
{
  float:left;
  vertical-align:top;
  width:170px;  
}

.page-layout .page-header .page-image div,
.page-layout .page-header .page-image img
{
  float:left;
}

.page-image-imgtop
{
  background-image:url('/Style Library/images/pagecontent-image-top-bg.png');
  background-repeat:repeat-x;
  height:6px;
  float:left;
  clear:both;
  width:100%;
}

.page-image-imgleft
{
    background-image:url('/Style Library/images/pagecontent-image-bg-left.png');
    background-repeat:repeat-y;
    float:left;
    text-align:right;
    clear:both;
}

.page-image-imgright
{
    margin-left:7px;
    padding-right:8px;
    background-image:url('/Style Library/images/pagecontent-image-bg-right.png');
    background-repeat:repeat-y;
    background-position:top right;
    float:left;
    clear:both;
}

.page-image-imgbottom
{
    background-image:url('/Style Library/images/pagecontent-image-bottom-bg.png');
    background-repeat:repeat-x;
    height:6px;
    float:left;
    clear:both;
    width:100%;
}

And the following HTML:

<div class="page-image">
 <div class="page-image-imgleft">
  <div class="page-image-imgtop">
      <img src="/Style Library/images/pagecontent-image-top-left.png" style="float:left;" />
      <img src="/Style Library/images/pagecontent-image-top-right.png" style="float:right" />
  </div>
  <div class="page-image-imgright">
   <img src="MAINIMAGE.jpg" style="border-width:0px;text-align:top;" />
  </div>
  <div class="page-image-imgbottom">
      <img src="/Style Library/images/pagecontent-image-bottom-left.png" style="float:left;" />
      <img src="/Style Library/images/pagecontent-image-bottom-right.png" style="float:right" />
  </div>
 </div>
</div>