In January 2009 players were suddenly unable to launch the game. Mark Rein
, Vice President of Epic Games, Inc.
responded that this was not related to the game's DRM. Instead, the online cheat detection features are based on digital signatures. The executable was signed with a certificate that expired in a way that it broke the game. The company eventually released a patch that solved in the problem, but in the meantime it could be resolved by changing the computer's system time to an earlier date.