While editing a Confluence page using either IE 11 or IE 10, put your cursor halfway down the page and try adding an emoticon. See that it resets the cursor to the top of the page and puts the emoticon up there as well.

Additionally, highlight text and select the bold option, again the cursor will reset to the top of the page.

Can only reproduce using IE. On Confluence version 5.9.8

Looks like CONF-31613 was a similar issue that says it's resolved, but I'm still seeing the issue