It appears that fadeIn();, fadeOut();, and fadeTo(); (and any of the opacity animations) are having issues in Internet Explorer. After troubleshooting for a couple hours, I discovered that if you add .css('display', 'inline-block') then everything appears to work, but with some obvious display hiccups.

Once I discovered that, I reverted back to see if setting 'inline-block' on the elements in CSS would improve the issue. Ironically, if I set 'display: inline-block' in CSS on the offending elements, nothing happens. I discovered that it didn't matter because something is adding a style to the tag as 'display: inline;', although 'display-inline' is not hard-coded in the document's tag. Due to something inserting 'display: inline;' into the tag (likely jQuery since it's the only library I use), it's likely overriding CSS, similar to if it were hard-coded into the tags.

If someone else wishes to play around with my theory and file a bug report or one of the developers sees this, feel free. Perhaps it'll help someone locate the issue in the library. Extremely annoying bug.

This is with the latest jQuery 1.4.