I am not sure what I did that led to this error. I was simply doing some typing in TextEdit and some web browsing. Then while trying to open a pdf file, this happened. Then I tried opening some other picture files and it was the same error. Basically, Preview.app stopped working and kept giving me this -600 crash error.
To fix this, you need to reboot. Yea, I know, I ran out of ideas, so rebooted, and the error went away. Hope this helps!