[ubuntu] Error while trying to run "sudo apt-get update"

Hello,

I'm ruing ubuntu 14.04.4 LTS. When I run the command
sudo apt-get update
in order to update my system, I get the following error message at the very end of the resulting output:

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/...-i386/Packages Hash Sum mismatch

E: Some index files failed to download. They have been ignored, or old ones used instead.

I have been seeing this error message since this past Sunday (May 29, 2016). Can someone please help me fix this error?