I don't know how to help with that, but it seems you'd be better off posting in the support forum. Barring that, I'll try to summon some help: @Moegreche@MrDayCee@Ferret@Tasselfoot@Hahiha@Boppins and @SoulGame for good measure.
Hopefully one of them can help you.
Also, is there a play button showing up and knocking over the kobold when it hits 100% and nothing happens when you click, or is it just not showing? (Just to get some info for the real support team to work with...)
I've been having a lot of issues with games on Firefox. Switching to Chrome has, for me, cleared up all of them. I have no idea what the deal is, but Chrome is just more stable in this respect, it seems.