Bespoke submit button

Hi I don't know if this is just me, but I have a very serious problem with my questions. We have made courses for a variety of clients with bespoke submit and previous and next buttons.

In testing I have just found that if I click the 'submit' button with out selecting an answer option the usual warning pops up, but when I click to close it - the player previous and next buttons appear, and the whole question locks so I can't answer the question any more. Also if I use amy of the back and next buttons to move from the screen and return the question is still locked, and my bespoke back and next buttons are hidden.

We did have a previous problem of the player buttons showing up if you went back to a question that had already been answered - and so on the slide master we put triggers saying to hide the player back and next buttons, which solved that problem, but this is a new problem we have only just found.