The following Tech-Recipes tutorial contains a trick for selecting “no to all” in Explorer.
When copying files in Explorer, you are often asked if you would like to overwrite files. Your options are yes, yes to all, no, and cancel.
You might ask, “Where is no to all?”
If you are copying a large number of files and do not want to overwrite any of them, you need to press no, no, no for every file.
Here is the trick to avoid this:
Hold down SHIFT when you click no and Explorer will act as if you just pressed a magic no to all button.