Earlier in the week Gearbox released an update for Borderlands: The Prequel alongside the official launch of the latest DLC, Lady Hammerlock Pack. Unfortunately the update broke a very important part of the game: The Grinder. Putting three items of purple rarity into the Grinder has "the potential to cause a crash." At the time Gearbox warned players who had already updated to not use The Grinder in game until a fix could be applied.
Today the developer released a hotfix to deal with the issue, but it says that a full blown update is still in the works.