I don't quite understand the bug - could you post steps to recreate? For me submitting a wrong answer shows the conjugation table, then takes you to the next question :/
Perhaps it's a Firefox problem? I'll try it in Safari (EDIT - seems to only trigger in Firefox, so might be a plugin conflict or something weird - probably wouldn't worry too much).
1) Load site, play
2) Get verb wrong - shows the hint table
3) Get to next question, first character entered into the box submits the form (usually incorrectly, of course!)
4) Normal behaviour resumes if I hit quit and play again
I don't quite understand the bug - could you post steps to recreate? For me submitting a wrong answer shows the conjugation table, then takes you to the next question :/