Got a call from someone whose IE was not displaying anything properly. The page background colors were blank, she couldn’t see a lot of controls or text boxes on web pages, and the fonts on web pages were all set to some messed up Lucida variant.
It turns out she had overridden what the web pages display with her own choice of formatting.
Tools > Options > General > Accessibility > Ignore colors specified on web pages
Tools > Options > General > Accessibility > Ignore font styles specified on web pages
Both need to be unchecked. Putting a check in either box overrides what web sites intend to display.