After applying the Windows Update (cumulative security updates for IE) on December 15th, the rectangle (and circle) for selections don't appear anymore. Even some feature layers don't show. I thought it was my application until I noticed the same problem with the ESRI Javascript sample below. This works in Firefox and Chrome, but not IE.
It looks like there may be some issues displaying VML after applying the security update. Here's a forum thread from Internet Explorer Tech Center regarding this issue:
