Unable to patch to address the issues
PlayStation 3 owners that are fans of Call of Duty: Modern Warfare 2 are finding that the multiplayer modes of the game are running wild with hackers and cheaters. The root cause is the recent release of the master security key for the PlayStation 3, and hackers are using this access to do what they can to wreak havoc in the multiplayer modes of the game.
The hackers have found a way to place players into hacked servers. These hacked servers, of course, will frustrate the heck out of most players, but it can also have the ability to wipe player stats. Because the CODMW2 title relies on the Sony security and encryption systems that are a part of the PlayStation 3, little can be done to address the issue at this time unless by some miracle a solution or patch is issued by Sony to fix the exploit; but this does not seem likely from what is known at this time.
Right now, Activision has no ability to restore or adjust any stats that might be lost by PS3 users. Activision is suggesting that users submit a “grief report” with PSN so that they are aware of the issues beyond playing private games with friends or just playing the single player modes, or playing Black Ops (which does not rely solely on the Sony security, but has its own security).
The problems with CODMW2 are unique to the PlayStation 3 platform security issues and the issues do not affect either the Xbox 360 or PC versions of the game.