Seems there is a slight bug in the alternate character sheet that they released (can be downloaded here:wizards.com/dnd/Tool.aspx?x=dnd/4new/tool/charactersheet wont let me create a link). If you look at the alternate character sheet the Investigation skill and the Medicine skill's checkmark to show you are trained in it), are linked. When you click on one the other is selected too, and when you de-select one both are deselected. No reason in the rules that I can tell that this should be the case.