我无法在 Ubuntu 软件中心安装任何东西，因为它会告诉我这是一个“不受信任的软件包”。我还去了软件源来“重新加载”，但它给了我这个：
Could not download all repository indexes
The repository may no longer be available or could not be contacted because of network problems. If available an older version of the failed index will be used. Otherwise the repository will be ignored. Check your network connection and ensure the repository address in the preferences is correct.
Failed to fetch http://ppa.launchpad.net/ubuntu-advertising/uadvt/dists/<source.changes>/ubuntu/maverick/binary-i386/Packages.gz 404 Not Found
Failed to fetch http://ppa.launchpad.net/ubuntu-advertising/uadvt/dists/<source.changes>/ubuntu/main/binary-i386/Packages.gz 404 Not Found
Some index files failed to download, they have been ignored, or old ones used instead.
答案1
从您的错误消息来看您添加了此 PPA，其中不包含任何包。这就是导致这些问题的原因。要解决此问题，请转到应用程序 -> 软件中心 -> 编辑 -> 软件源 -> 其他软件并取消选中以下条目：
deb http://ppa.launchpad.net/ubuntu-advertising/ppa/ubuntu maverick main
deb-src http://ppa.launchpad.net/ubuntu-advertising/ppa/ubuntu maverick main
