Mavericks cannot open/read RAW files

Just upgraded to new MacBook Air with Mavericks. Moved my photo library over, and cannot read any of my RAW photo files (neither Canon CR2 nor Nikon NEF).

System is up to date, including latest Digital Camera Raw Compatibility Update (5.04). Based on several posts I found, I already tried to remove the Camera Raw Update and install older versions, restarting the machine. No change.

OS (Mavericks) does not open/read the files with either Preview or Quicklook - shows a black background. Applications don't open/read them either (tried both Aperture - which says "unsupported image format" despite rebuilding the library and trying all other things - and iPhoto - which also just shows a black background image), but since Preview doesn't even work, it's clearly an OS problem.

I'm very frustrated... Most grateful for any suggestions.