Edit labels icon doesn't show up in IE7

Under IE7, the new icon for editing labels (used to be a word "Edit") does not show up. It does appear in IE8, Chrome 10.0 and Firefox 3.6 therefore must be an IE7 thing.

The only way for users to edit labels is to edit the page, which is not how it was in 3.4.7 which we had before.

Unfortunately our corporate SOE is IE7 so I can't just tell people to upgrade their browser. This makes it not possible for us to upgrade to Confluence 3.5.