I have had a problem with the display of the official Twitter widget in IE at work - took a look at the site and see it is a problem here as well. After trying all types of solutions posted on the web the final solution for me was just to use IE conditional tags and post alternate content. I used both the widget and RSS for two reasons. The ability to grab the rss feed is undocumented and may be killed by Twitter at some point and because the widget display is nice so I want to use it if available.
<!--[if IE]>
//hide the div containing the widget if it doesn't collapse
<style>#TwitterWidget{display: none}</style>
<div id="AlternateTwitterRSSforIE">
//your code or widget to grab the unofficial
//Twitter rss data for your feed. Here is the syntax
http://api.twitter.com/1/statuses/user_timeline.rss?screen_name=your-twitter-username
<![endif]-->
</pre>
You would paste your Twitter supplied code block below this.
<div id="#TwitterWidget">
//Twitter supplied code goes here
</div>
If Internet Explorer is detected then that conditional block will display and with the style display: none we prevent the regular Twitter widget from showing to be safe. If it isn't IE it just skips that section and widget displays normally. You can use CSS to make the RSS feed and Twitter widget look similar.
