You went radiation scanning on New Romulus, didn't you? This bug's been there ever since New Romulus came out. If you do the radiation scan mini game, it breaks the dilithium mining mini game. Either you have to go mining first, or you have to exit the game and log back in to clear it.
This character is why I don't play my Romulan any more. Tovan Khev is NOT my BFF! Get him off my bridge!