hacked games permanently change mw2??

[lockdown6435]

Sometimes when i join a hacked game, my game will keep certain aspects of the game permanently. for example, names on my menu are block letters and flash red and blue, i have no crosshair, and my sound is completely changed. How can people permanently change my game just by entering their server once, and is there a way to fix this and prevent it in the future??? (Ive already tried full reinstall, and that didnt work)

Thanks

Delete mp config. Some things can be changed without that much effort with MW2 Config.