It is always a challenge when developers are forced to deal with game-breaking exploits and bugs, but MMO developers have it the hardest. Neverwinter is the latest of the bunch to fall prey to a group of players that have managed to exploit the Astral Diamond currency of the game.
According to a post by an Administrator at publisher Perfect World's forum, "Early Sunday morning a very small group of players discovered and abused a game exploit within the Neverwinter Open Beta that affected the Auction House and Astral Diamonds."
In order to undo the immense damage done to the in-game economy after a nearly endless amount of money entered the game, Perfect World "took the Neverwinter OBT down for emergency maintenance, found the bug, corrected it and tested it. In order to fix the damage this exploit caused to the in-game economy, we implemented a necessary rollback of our servers to 5:20 AM PDT the morning of May 19, 2013. This means that characters have been reverted to the state they were in at that time, pre-exploit damage. That includes items, level, experience, etc."
That means seven hours of lost progress, which is unfortunate for any players that were playing at the time of the exploit, but keep in mind this is still Neverwinter's open beta. Also, to make up for the lost time, Cryptic and Perfect World released the Caterday Survivor's Pack which includes: Stone of Health, Cape of Catastrophe, Dwarven Facemask, 5x Teleport Scroll – Protector's Enclave and 2x Adventurer's XP Booster. As Perfect World notes, "All characters that have been created before 5AM Pacific on Sunday, May 19, 2013, will receive the Caturday Survivor’s Pack, which will appear in your in-game mail as an attachment to the message, “You Survived!” The items within the Caturday Survivor’s Pack are bound to each character that receives it."
One of the major issues with the exploit was not only the effect on the in-game economy, but also the real money currency, called ZEN, which meant the influx of "billions upon billions of new diamonds meant Zen prices crashed." It appears that the issue has been patched now, but it might be a few days until the game is fully operational again.