This can be caused by two issues.

One cause is that you need to add this line of code in the Meta Tags section of the Page Wrapper:
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />

The other cause of this can be if the HTML was copied from Microsoft Word.  If this is the case there is a lot of extraneous code that gets added, and Internet Explorer will try to render it and fail.  To fix this, remove the extraneous code from the HTML.