After installing mono-complete on my Ubuntu 11.10, something got corrupted in the package catalog. Whenever I try to install
emove anything I get an error and told to use apt-get -f install. I get the same thing from the GUI. When I try to do it, I get the following error:

Reading package lists... Done

Building dependency tree       

Reading state information... Done

Correcting dependencies... Done

The following extra packages will be installed:

  mono-devel mono-xbuild

The following NEW packages will be installed:

  mono-devel mono-xbuild

0 upgraded, 2 newly installed, 0 to remove and 83 not upgraded.

2 not fully installed or removed.

Need to get 0 B/2,256 kB of archives.

After this operation, 9,048 kB of additional disk space will be used.

Do you want to continue [Y/n]? Y

(Reading database ... 269743 files and directories currently installed.)

Unpacking mono-xbuild (from .../mono-xbuild_2.10.5-1_all.deb) ...

dpkg: error processing /var/cache/apt/archives/mono-xbuild_2.10.5-1_all.deb (--unpack):

 unable to open '/usr/lib/mono/4.0/xbuild.exe.dpkg-new': No such file or directory

No apport report written because MaxReports is reached already

                                                              Unpacking mono-devel (from .../mono-devel_2.10.5-1_all.deb) ...

dpkg: error processing /var/cache/apt/archives/mono-devel_2.10.5-1_all.deb (--unpack):

 unable to open '/usr/lib/mono/2.0/al.exe.dpkg-new': No such file or directory

No apport report written because MaxReports is reached already

                                                              Processing triggers for man-db ...

Errors were encountered while processing:

 /var/cache/apt/archives/mono-xbuild_2.10.5-1_all.deb

 /var/cache/apt/archives/mono-devel_2.10.5-1_all.deb

E: Sub-process /usr/bin/dpkg returned an error code (1)

I understand that I'm missing some mono filesdirectories, but I can't reinstall mono because apt-get just tells me to run apt-get -f install - which doesn't work.

How can I fix this?

UPDATE

Running apt-get update gives me the following errors:

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/edgy/universe/source/Sources  404  Not Found [IP: 91.189.88.46 80]



W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/edgy/universe/binary-i386/Packages  404  Not Found [IP: 91.189.88.46 80]



W: Failed to fetch http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu/dists/oneiric/main/source/Sources  404  Not Found



W: Failed to fetch http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu/dists/oneiric/main/binary-i386/Packages  404  Not Found



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