The APEX 5.1 icons are missing when using Windows 10 with the following browsers IE v11, Google Chrome v65, Mozilla Firefox v59. On Windows 7,using Chrome, the login form is displayed as:

on Windows 10, the login form is displayed as

The square outline continues across all forms

all icons are square outlines.
This is happening on Windows 10 pcs
Has anyone else had this problem and if so, what configuration what changed to correct this?
Thank you
Linda