Border is unexpectedly broken in IE 6.x

I'm having an odd problem getting this style to work properly in IE 6.0:

border: 1px solid black;

The problem comes when I float (left or right) a <div> within a <div>. The border gets broken up by the nested, floated <div>. An example is on this page:

http://www.thsalumni.com/Alumni.aspx?ID=281

Here, the "photo div" has two photos, both within nested divs and floated left and right. The border around the "photo div" is partially wiped out.

Note that in Firefox, Opera, and Mozilla I have no problems.

Any ideas how to fix this? Thanks for any help!

--Brent