by Guillermo Madero S..
Hi Mark,
Unfortunately this issue seems to depend on quite a number of external factors. I have visited sites where the user reported having that problem and I could expand the links Ok. I have also had that problem myself, which I solved by downgrading FF from version 15 (back then) to version 14. Very nasty situation.
I saw you wrote at the tracker. I suppose that people need to vote again to have that tracker reopened.