apt-get error

ubuntu 11.04

apt-get更新的时候发生一个问题：

'E:Encountered a section with no Package: header, E:Problem with MergeList /var/lib/apt/lists/cn.archive.ubuntu.com_ubuntu_dists_natty_main_binary-i386_Packages

#rm -rf /var/lib/apt/lists/*

#apt-get update