Certain sites temporarily breaks back/forward gesture

This has been happening to me for as long as I've used strokeit. Going to certain sites renders the left/forward gesture on firefox browsers unusable for a random amount of time. I don't remember all of the sites but one site that always does it for me is Youtube and other sites with flash videos.

Anyone have the same problem? I don't think it's my computer since this happened on my old computer, on my laptop and now my new computer on both XP and Win 7.

That is a more or less known issue, without a proper solution yet. It has been mentioned already a few times.
You can read some hints here:
http://www.tcbmi.com/strokeit/forum/read.php?3,53733,53742#msg-53742