Double click on your move tool icon and scroll down to Soft Select and make sure it is turned off... maybe that will do the trick, but it doesnt look like you have it turned on :s To check whether soft selection is switched on, try converting your selection from edged to vertices - move the vertices and see if it is still behaving the same way, if yes, then the culprit is soft selection..... Alternatively you can also delete your maya preferences and restart the software, it will reset all the settings to "factory settings". You don't really know what helps here !!