I installed Ubuntu 11.04 in VirtualBox on Windows Vista and had Refreshed in Synaptic Package Manager, then received this error:
Could not download all repository indexes
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.
Failed to fetch http://us.archive.ubuntu.com/ubuntu/...ty/Release.gpg Something wicked happened resolving 'us.archive.ubuntu.com:http' (-5-No address associated with hostname
And a longer list of paragraphs like the last one.