Why is Safari on my computer rendering all of the colors -- not just for images -- incorrectly?

I’m not just talking about image color profile issues; every single color that the browser renders is incorrect. It’s like it’s in it’s own color space (or something!).

Screenshot: http://drp.ly/DJk1O (Opera, Safari, Chrome, Firefox)

Spot the odd one out? Open this up in Photoshop or similar and try using the eyedropper to select the colour. Safari renders the same hex color completely differently. That color is set using a background-color declaration in CSS, so it should be identical in all four of those browsers.

Here’s the HTML file I was using: http://drp.ly/DJn5k

Literally every website I’m viewing with my install of Safari is displaying colors incorrectly. Here’s Facebook, notice the blue of the bar: http://drp.ly/DJD6m (Chrome on the left, Safari right)

This doesn’t occur on any other Macs I’ve tried. Any idea what’s happened to my Safari install?