11.10 apt-get update error

error message

http://download.virtualbox.org/virtualbox/debian/dists/oneiric/Release 파일을 받는 데 실패했습니다  Unable to find expected entry 'contrib/source/Sources' in Release file (Wrong sources.list entry or malformed file)
Some index files failed to download. They have been ignored, or old ones used instead.

source repo delete!
and update.

출처;
https://forums.virtualbox.org/viewtopic.php?f=7&t=41251