Why i can not download the versions of minecraft ?

I do not manage to play minecraft since its update of January which made him change appearance then it had to reloaded the versions and when I do it it tells me:
Unable to save download. el_GR.lang
name : el_GR.lang
Link :http://resources.download.minecraft.net/a2/a2a737070bd9d9fb62b7b849479d9ec49c51c3eb
Details of the error : Attempting to move successful download to C:/Users\everybody\AppData\Roaming\.minecraft\assets\objects\a2/a2a737070bd9d9fb62b7b849479d9ec49c51c3eb
The process can not access the file because this file is used by another process
The process can not access the file because this file is used by another process
Name of the file on disk: a66c-3250-e381-c836
access path: C:\Users\tous\AppData\Local\Temp\a66c-3250-e381-c836
Existe : file