最近更新lubuntu, 出现了这个错误，怎么破？

[温习江湖]

代码： 全选

W:Failed to fetch bzip2:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_source_Sources  Hash Sum mismatch
, W:Failed to fetch bzip2:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_binary-i386_Packages  Hash Sum mismatch
, E:Some index files failed to download. They have been ignored, or old ones used instead.

都几天了，以前也遇到过一次

[mraandtux]

看下面的链接：
http://askubuntu.com/questions/166642/s ... check-time

[温习江湖]

看下面的链接：
http://askubuntu.com/questions/166642/s ... check-time

sorry, 照着里面说的做了，无效