I don't know how to replicate it but when I looked at google analytics there werre dozens, maybe hundreds of those "fragment" URLs and if I followed those URLs sure enough I got the blank page... This means some people were also getting blank pages- now none of my members complained so maybe it was random visitors... I don't know.To be safe I removed all Facebook elements from my threads but I kept the like button on my homepage.
As a backup I did implement the channel url fix. It involves making a new blank HTML file with the 1 line of code mentioned on the page that describes the fix, then adding extra code to the facebook code... i wont know if its working until a few days go by and i don't see anymore fragment urls.
in the mean time i added the share button from
www.addthis.com which has facebook, twitter, and 200+ other sites to share with, but a custom javascript so shouln't be affected by this bug,