Only just become a problem today, https everywhere version 3.5, firefox 28.0
Do you have the full URL that is hanging? Not all site assets are currently available over HTTPS.
HTTPS Everyone has a broke ruleset that is redirecting to a 404 page:
<rule from="^https?://www-cdn\.jtvnw\.net/" to="https://justin.tv/" />
Looks like there is a patch to fix it waiting to be merged.
I’m having the same issue, pls help!