mw2 liberation is a false possitive, which makes ur virus protection pick it up as a virus. when you downloaded it you probably disabled ur virus protection and now its enabled... so it picks it up everytime, when you log into your account on computer just disable it before u use it, thats what i do. ITS NOT A VIRUS!!
when you get the error "Unable to communicate with modern warfare 2 liberation module, Please try again" means that when your virus protection picks up a virus or in this case a false possitive, it quarantines the files. then removes them from the specified location for mw2 liberation, making it not able to find the proper files to run it... hope this helped