Check carefully to see that the text that you have defined in the design is editable. There's a pretty bad bug being worked on by Adobe in which the various text in the document gets shuffled. That came to mind because "str" could mean "string", which is programmerese for text.
If you've got FontExplorer X Pro installed, try disabling the font requests and re-enabling them.
I figured it might be something to do with that from the previous replies, and I can't trigger the bug anymore.
Not necessarily the cause, but it seems to be working OK now
How does deleting the FontExplorer extension effect your use/operation with FontExplorer & Photoshop (or Illustrator)? I also want to get rid of this bug but need to continue to utilize FontExplorer to manage fonts... Thx
Actually the problem is this; a few versions prior to 10.8/CS6, Fontexplorer would automatically launch the application if it wasn't running to match up any missing font. I'm not sure if its because its a older version and/or adobe has ceased letting the application fire open when photoshop/illustrator is triggered but it almost 100% of the time I get this error it's because Fontexplorer isn't open yet and it's trying to launch it but its no longer allowed to launch the application... thus the 'Strtble Error.' If you have Font Explorer opened and try the same file you won't get the error, and viceaversa you'll get the error if you don't have it open.
I'm still running an old version of Font Explorer (3.1) with CS6 I assume all of my issues are contributed to that. I'm not sure if the same thing happens on new versions of Font Explorer. (I have a fear of updating since it destroyed all of my folders the last time I updated.)