When facing an unsolvable problem restarting from scratch could be a utterly wise decision. First unzip Blender again, then delete all packed MHX-files in the add-on folder. Then get MHX-2, the FAQ will help you and put it to the right folder. Same goes for MakeWalk, -Clothes. etc.
BTW: I'm not sure what you are doing with blender, but it seems as if your in animation. If your hardware is only roughly as old as your OS, you might run in other big trouble, or in short words: you can't exaggerate with system power in this field of application.