I haven't heard about it affecting the client computer; however, there is some type of 'admin' bug that allows a player to take on the role of administrator, to put out popups to players screens, to change names, to change weapons, and to kick players. From what I have read they do this by modifiying one of the .u files...I honestly hope they (DEV's of AA : O) weren't foolish enough to handle authentication for things like that on the client side *shudder*

/nebulus200

AKA kronos200 on AA:O

EDIT: Apparently the developer's have a work-around until they release PunkBuster, to the effect of scanning the game files for alterations that could result in banning of the offenders...

Read here