I have about 6 hours play and I have had no problems, but now whenever I sell anything (1 item or 15) to Moira, after I complete the transaction, the dialogue choice box disappears and I can't do anything as I have no way of exiting. I've tried exiting the store and re-entering as well as loading the auto save multiple times.

Are you using any mods?

No mods. If it means anything, the game is off Steam, not a disc.

Does it happen with other vendors?

Fixed. Guess it was a matter of spending a few hours doing other tasks.