One of my managers uses Internet Explorer and has the following strange behavior when trying to edit the Sales stage in a Potential:

The "Edit" hyperlink appears correct when hovering over the Stage (Closed/Won, Analysis etc) but, as soon as you move towards the "Edit" Hyperlink, this disappears so there is no way to edit the stage.

This works perfectly in Chrome, haven't tried in Firefox but most definitely doesn't work in IE.

The workaround is to use the top "Edit" button but it's a bug nevertheless.