Bungie has banned "several dozen" Halo: Reach players who "habitually" idle or exhibit "AFK behaviour" (go away from their console) while playing Firefight Matchmaking.
Those in the firing line are invited to contest the credit reset. But doing so needlessly could land you a credit ban.
"So far we have issued extended credit bans for several dozen accounts," wrote Bungie "Fungineer" Jeremiah on the game's forum. "We are continuing to look for false positives but so far no one has been reset and banned without sufficient cause.
"It's clear that even players who know they're deserving of this ban are going to request an investigation, which could end up delaying the investigation of a player who is honestly unaware of why they were reset and banned."
"I ask that you please remain patient while we continue to review disputes and we will notify players individually if we require any additional information from them."
Firefight is a wave-based multiplayer mode for Halo: Reach, in which players fend off increasingly tricksy hordes of Covenant baddies. The video below shows Eurogamer attempting this alone, without any real trace of skill.