Illustrator :: Program-wide Color Change Across CS6

I'm in OS X 10.8.3 working in Illustrator CS6. I have a MacBook Pro hooked up to a calibrated NEC PA271W monitor.
 
I've been working on some CMYK design documents with a mix of process and Pantone. All art was created in Illustrator and is vector. Everything was going fine, colors looked great and super-accurate as they always do with this monitor. Then...
 
I was exporting my design to PDF via Save a Copy. As I always do for PDFs I'm sending to a client for review, I chose to convert the colors to destination sRGB in the PDF options dialogue so they can be reviewed on screen.
 
Upon viewing the PDF using QuickLook in the Finder, I noticed that—rather than being converted to sRGB and looking pretty-close to the CMYK AI file—the PDF was extremely dull as if all colors had been desaturated 50%.
 
I tried other variations of the export and could not get the colors to look right (note: I did the exact same exports many times over the last week and they always looked great). Finally, I restarted my comp thinking perhaps it was just a temporary bug.
 
Upon opening my design file back up in Illustrator -- all the elements in the design file itself as we'll as ALL color palettes within illustrator had the same horrible desaturated look! CMYK proof preview was not turned on it affects all files, even those that worked perfectly in the past. I didn't knowingly change any settings in Illustrator (is there a make-all-colors-look-grayed-out shortcut I don't know about?!).
 
Things I've tried:
Trashed all custom color profiles and re-calibratedTrashed all ColorSync prefs and cacheRan ColorSync validation on all profiles, fixed those with problemsChecked that CS6 color was synchronizedChecked that all profiles on documents were correct (though I knew it wasn't this because of the random nature of the change.Restarted my Mac a bunch of times.Ran Onyx automated cleaning.