12.04 - failed to update - internet connection error

i am using ubuntu 12.04 lts.
i m trying to update but i get an error

Failed to download repository information
Check your Internet connection.

My internet connection is fine.

when i see details of the error an get this

W:Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release Unable to find expected entry 'main/source/Sources' in Release file (Wrong sources.list entry or malformed file)
, E:Some index files failed to download. They have been ignored, or old ones used instead.

any help please