I am having errors loging in to minecraft. I am logged in, but I can not launch the game.

Here is the bug:
Unable to save download. br_fr.lang
Name: br_fr.lang
URL: http://resources.download.minecraft.net/8d/8dfff044644adf4de0a1b8fe334a47eaed0a65ff
Error details: Attempting to move successful download to C:/Users\Rob\AppData\Roaming\.minecraft\assets\objects\8d/8dfff044644adf4de0a1b8fe334a47eaed0a65ff
The process cannot access the file because it is being used by another process
Filename on disk: 2e5b-c99f-3be4-3cf3
Path: C:\Users\Rob\AppData\Local\Temp\2e5b-c99f-3be4-3cf3
Exists: file