Missing packages

[Bruce Wilkinson]

I'm using Add or Remove Packages, trying to install any of the
development tools. In each case, I get "Packages Not Found" error. The
occurs with all of development packages, although the missing packages
differ slightly.

Some of the frequent missing packages are libselinux, krb5-libs, pam,
libxml2. Oddly enough, if I go get those packages and try to install
them, I get an error indicating the packages are already installed.

Does anyone know what's wrong?

Bruce