Ah another hasLayout quirk
it's not possible to achieve in IE7 and still retain the width of the span, if you could show what you're trying to achieve in a JS fiddle perhaps we could help, find a way around it e.g. and this is only a guess, putting the width on the anchor
with some padding would help create a completely clickable area and still allow a "caption" span to be restrained if that's what you're after..
Example workaround not a fix
CSS:
a {
display: inline-block;
background: #ff0;
max-width: 50px;
padding: 10px;
text-align: center;
}
img {border: 0; display: block; margin-bottom: 10px;}
span {line-height: 1.5;}
HTML:
<a href="#">
<img width="50" height="50" src="http://dummyimage.com/50x50/000/fff" alt="">
<span>Some text and even longer</span>
</a>
The above is only a thought, and if it's not what you're after, then please provide a sample jsfiddle.net