When I'm walking around in the Lost Grove, everything works fine up until I get into a fight.
The fight seems to work fine too, but afterward when I take one step every button in the interface locks-up and the arrows are all dark. (like when there's an obstacle)
It happens every time; I've also noticed that the buttons become equally unresponsive (but the arrows are still lit and don't respond to mouse rollover) after switching party positions after the fight instead.

Reloading the page resets the interface and everything seems normal again, until the next fight.

I'm using Mozilla Firefox version 40.0.3.
I tried clearing my cache, but it didn't seem to help.

Is your browser up to date?

Are there any addons you could try disabling to make sure they aren't tampering with the page?

Have you tried a different browser to see if the issue persists or is isolated to Firefox?

I updated Firefox to version 43.0.1 and nothing changed, then updated again to version 47.0.2 and it seems to be fixed.
I had also used Google Chrome to test and it worked fine there too, it updated itself after I used it so I don't know what version it was.

So whatever it was, updating firefox seems to have fixed it.
Thanks, Krinadon.

Awesome. =)