Crash Guard
When MicroSoft released Allegiance it incorporated a feedback system for reporting crashes. Whenever a player's game crashed, it would automatically load a web page called Crash Guard asking for details, and the details would get forwarded to the MS dev team.
The Crash Guard bug
Crash Guard became infamous in 2001 when Your_Persona, the leading member of My Allegiance, released a patch that allowed players to use custom voice chats. Unfortunately he didn't realise prior to release of his patch that any players who didn't have a copy of the custom voice chat would get Crash Guarded whenever someone else used them.
Unethical players - most notably Virus, Black, and Guns22 - used this bug to annoy other players. By joining a game in progress and broadcasting a custom voice chat to "All" they could crash everyone at once, devastating entire 40-60 player games.
SOVGuard was designed to protect against Crash Guard attacks, but the damage was already done. The majority of players had left Allegiance.
