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.

Are you having problem with updating your Linux OS?
You could not download all repository indexes for your laptop/PC after you attempted to download updates.
You got these error messages.

"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."

E: Malformed line 11 in source list /etc/apt/sources.list (absolute dist)
E: Unable to lock the list directory

E: Malformed line 11 in source list /etc/apt/sources.list (absolute dist)
E: The list of sources could not be read.
Go to the repository dialog to correct the problem.
E: _cache->open() failed, please report.

ERROR###ERROR###ERROR###ERROR###ERROR###ERROR###ERROR
E:Malformed line 11 in source list /etc/apt/sources.list (absolute dist)

After checking my source list at /etc/apt/sources.list:

deb http://packages.linuxmint.com/ lisa main upstream import
deb http://archive.ubuntu.com/ubuntu/ oneiric main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ oneiric-updates main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu/ oneiric-security main restricted universe multiverse
deb http://archive.canonical.com/ubuntu/ oneiric partner
deb http://packages.medibuntu.org/ oneiric free non-free

#deb http://archive.getdeb.net/ubuntu oneiric-getdeb apps
#deb http://archive.getdeb.net/ubuntu oneiric-getdeb games
deb http://www.linuxmint.com/repository romeo/
deb http://www.linuxmint.com/repository romeo/ apt-get update

If you found the last two lines in your resource.list at /etc/apt/;
remove that, the dev http://www.linuxmint.com/repository romeo/
and htttp://www.linuxmint.com/repository romeo/ apt-get update.

You can easily remove that by editing the file with the root privileges. Go to the directory /etc/apt/ and then

type this code in the terminal sudo gedit resource.list.

Be sure you that your prompt for the terminal is the same directory of the file.

That's it.