Unable to play Call of Duty Modern Warfare Multiplayer

Ever since the Call of Duty optimization update a couple of weeks ago, I have been having massive lag issues and unable to play multiplayer on certain maps. I will get a Dev Error and then the map name next to it. This happens only for certain maps that I have played before the update. I am unable to play them now. I have checked for updates and asked other friends. They are experiencing the same issues and just won't play the game anymore.

I have contacted customer service and they have provided no help at all. All they say is to restart my modem and unplug/ plug back in my xbox. That did nothing at all.

What more can I try besides uninstalling the entire game and reinstalling. That is not a feasible option for me.

:)