When I was trying to upgrade my server from ubuntu 10.04 to 12.04 I was facing problems with some packages. It was saying,
sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
You might want to run `apt-get -f install' to correct these.
The following packages have unmet dependencies:
gcc-4.4: Depends: gcc-4.4-base (= 4.4.7-1ubuntu2) but 4.4.3-4ubuntu5.1 is installed
Depends: cpp-4.4 (= 4.4.7-1ubuntu2) but 4.4.3-4ubuntu5.1 is installed
Depends: binutils (>= 2.20.1-15~) but 2.20.1-3ubuntu7.1 is installed
Depends: libgcc1 (>= 1:4.4.7-1ubuntu2) but 1:4.4.3-4ubuntu5.1 is installed
Recommends: libc6-dev (>= 2.13-0ubuntu6) but it is not installed
libnih-dbus1: Depends: libnih1 (= 1.0.3-4ubuntu9.1) but 1.0.1-1 is installed
libnih1: Depends: libc6 (< 2.12) but 2.15-0ubuntu10.5 is installed
E: Unmet dependencies. Try using -f.