Internet Explorer very persistently caches pages, deciding that it knows better even if the page is so much different.  As long as the page has the same URL, it will cache it.  The only way around it is to go ahead and change your name and upload a new avatar, and then click Save, and then empty your browser cache, close and reopen IE.

I'm still investigating a way around that, but it's looking like it'll be complicated because IE also ignores the "no-cache" instruction.  That means I have to find a way to make the page URL change each time it's loaded.

Another unforseen problem this probably causes is with edited posts.  I'm pretty certain IE people are not seeing changes to edited posts because of this.