有时，当我安装东西时，我会收到如下错误：
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed
E: Unable to correct problems, you have held broken packages.
我该如何解决这个问题？
package-management apt ppa dependencies software-installation
这是在 Ubuntu 12.04 服务器上。
尝试运行任何apt-get install（尝试安装不相关的任意包）时出现此错误：
dpkg: dependency problems prevent configuration of openssh-server:
openssh-server depends on openssh-client (= 1:5.9p1-5ubuntu1.1); however:
Version of openssh-client on system is 1:5.9p1-5ubuntu1.4.
dpkg: error processing openssh-server (--configure):
dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous failure.
dpkg: dependency probms prevent configuration of ssh:
ssh depends on openssh-server; however:
Package openssh-server is not configured yet.
dpkg: error processing ssh (--configure):
dependency …