Bridge has started opening all my files in mono. Most of my workflow is in RAW so I know that the file is in colour but when transferring from Bridge through Camera RAW to Photoshop it is automatically previewing and converting all files to black & white. Can's see what is causing this or how to reset it.
It's a long shot, but I don't suppose you have accidentally set Convert to Grayscale on by default in Camera Raw settings have you?
Open a Raw photo without any settings, in Camera Raw, and hit Ctrl-Alt- (or Cmd-Opt-) 4 and look at the checkbox at the top of the panel. It should be clear.
If it isn't, clear it, and click the tiny menu icon to the right, and select Save New Camera Raw Defaults.
It also sounds like the sort of thing that might happen if you had the wrong workspace profile selected. But, as far as I know, there have never been any mono options.