I use Moodle for online teaching, and after upgrading to Safari 6 (as part of my Mountain Lion upgrade) I found that I could no longer upload files to create download links for my students. I started receiving a JSON string error. To isolate the problem, I turned off half of my extensions, then the other half, etc. etc., and replicated the problem until I isolated a single extension that created the problem - and sadly, it was Evernote Web Clipper 5.6. I'm on a 2009 15" MacBook Pro running OS X 10.8. Anyone else having the same problem? Any fixes?