Comment 17 for bug 225165

This info may be of some use, tracking this bug down (considering it may have to do with javascript or browsers in general for the issue).

Javascript engine:
Firefox: SpiderMonkey (?)
Chrome: V8
Epiphany: Unable to say with any degree of certainty

Layout Engine:
Firefox: Gecko
Chrome: Webkit
Epiphany: Webkit

Can possibly be advisable to figure out:
Does problem occur on unity, gnome-shell, or other window managers, with or without compiz, e.g. with or without Ice Tea or other plugins installed?

Preliminary conclusion:
This does not appear to be a Ubuntu, Firefox, Flash specific problem, but a problem with a wider scope.

Recomended solution:
Further input and testing need. Working together with different affected and involved parties, liasioning where needed, to find and implement solution.