Ubuntu software mirrors seem to have issues (403 Forbidden)

Hi,
I have been trying to run "apt-get update" on a number of different Ubuntu 12.04 servers and I keep getting "403 Forbidden" errors from some (not all) of the software mirrors. I do not believe this to be a problem on my end since most of the mirrors work and only some fail. Plus the error suggests that the web server on the software mirror is not allowed to access to directory where the files are.

Err http://security.ubuntu.com precise-security/main Sources
  403 Forbidden
Err http://security.ubuntu.com precise-security/restricted Sources
  403 Forbidden
Err http://security.ubuntu.com precise-security/universe Sources
  403 Forbidden
Err http://security.ubuntu.com precise-security/multiverse Sources
  403 Forbidden
Err http://security.ubuntu.com precise-security/main amd64 Packages
  403 Forbidden
Hit http://lk.archive.ubuntu.com precise/multiverse amd64 Packages
Err http://security.ubuntu.com precise-security/restricted amd64 Packages
  403 Forbidden

  403 Forbidden
Err http://security.ubuntu.com precise-security/multiverse amd64 Packages
  403 Forbidden
Err http://security.ubuntu.com precise-security/main i386 Packages
  403 Forbidden
Err http://security.ubuntu.com precise-security/restricted i386 Packages
  403 Forbidden
Err http://security.ubuntu.com precise-security/universe i386 Packages
  403 Forbidden
Err http://security.ubuntu.com precise-security/multiverse i386 Packages
  403 Forbidden

Detais are :

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 12.04.1 LTS
Release: 12.04
Codename: precise

 uname -r
3.2.0-29-generic