Error on start up

XML Parsing Error: undefined entity
Location: chrome://browser/content/browser.xhtml
Line Number 743, Column 15:
<toolbarbutton id=“UITourTooltipClose” class=“close-icon”
Otherwise Developer has been error-free for me
This occurred on startup

This sounds like the following bug

It seems that creating a new profile fixed the issue for some users? It also sounds like we are having trouble diagnose the issue. So if you have time to comment on the Bugzilla link I added above, it might help us to fix it.