Hello,
when I try to install root I had that problem:

Code:
jeleff@jeleff:~$ sudo apt-get install root-system-bin
[sudo] password for jeleff:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  cfortran comerr-dev gfortran gfortran-4.3 libfreetype6-dev libftgl2 libkadm55 libkrb5-dev libpcre3-dev libpcrecpp0
  libpthread-stubs0 libpthread-stubs0-dev libroot-dev libroot-minuit5.18 libroot5.18 libx11-dev libxau-dev
  libxcb-xlib0-dev libxcb1-dev libxdmcp-dev libxext-dev libxi-dev libxpm-dev root-plugin-asimage root-plugin-gl
  root-plugin-proof root-system-common ttf-opensymbol x11proto-core-dev x11proto-input-dev x11proto-kb-dev
  x11proto-xext-dev xtrans-dev
Suggested packages:
  doc-base gfortran-multilib gfortran-doc gfortran-4.3-multilib gfortran-4.3-doc libgfortran3-dbg krb5-doc gccxml
  root-plugin-netx root-plugin-xproof
Recommended packages:
  libroot-minuit root-fitter
The following NEW packages will be installed:
  cfortran comerr-dev gfortran gfortran-4.3 libfreetype6-dev libftgl2 libkadm55 libkrb5-dev libpcre3-dev libpcrecpp0
  libpthread-stubs0 libpthread-stubs0-dev libroot-dev libroot-minuit5.18 libroot5.18 libx11-dev libxau-dev
  libxcb-xlib0-dev libxcb1-dev libxdmcp-dev libxext-dev libxi-dev libxpm-dev root-plugin-asimage root-plugin-gl
  root-plugin-proof root-system-bin root-system-common ttf-opensymbol x11proto-core-dev x11proto-input-dev x11proto-kb-dev
  x11proto-xext-dev xtrans-dev
0 upgraded, 34 newly installed, 0 to remove and 0 not upgraded.
Need to get 341kB/30.2MB of archives.
After this operation, 118MB of additional disk space will be used.
Do you want to continue [Y/n]? y
Err xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx pwnsauce/main ttf-opensymbol 1:2.4.1-11ubuntu2.1
  404 Not Found
Failed to fetch xxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ttf-opensymbol_2.4.1-11ubuntu2.1_all.deb  404 Not Found
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
xxxx is for archive.offensive-security.com ...
How can I fix it?