I'm working on a local install of EE 2.10.1 in Windows 7 with XAMPP. Everything is cooperating, but the control panel navigation is broken - mouseing over/clicking nav items shows no drop-down. It appears my JS and CSS are all loading. Default theme. Has anyone seen this before?
Uninstall all third party addons, especially Accessories. I literally had this happen to me the other day when I was developing a complex addon. I can't remember if it was the Extension or Accessory that was doing it (pretty sure it was the Accessory). Do them one by one so you can find out exactly who the culprit is.