Introductions to Drupal are mostly all about enabling modules to unleash new functionality, but it can be good to know when to let it go and disable a module instead.
It is this author's belief that the Overlay module should be disabled, because it necessarily breaks the way typical browser functions work. Firefox, for instance, typically preserves whatever data has been entered into a tab. Accidentally click a link and hitting a back button brings us back— with what we'd written. Close a tab, and Control + Shift + T brings it back— with any data we'd typed into it. With Overlay, a single misclick can banish our administrative form changes or unsubmitted 7,000 word node forever.
To disable the Overlay module, we visit admin/modules, find the Overlay module in the listing under Core, remove the check from the box next to it, and submit the form with the Save configuration button at the bottom.
Those with a less jaundiced view can leave the Overlay module enabled, and disable it for individual people on their user edit forms, such as user/86/edit.