There are some new updates in Ubuntu.
Happy you want to install them.
But a strange messages raises asking to insert the release cd in /media/cdrom.
How to solve it:
- start Update Manager
- click Settings button
- on each tab verify the all cdrom mentions to *NOT* be checked. If are, un-tick them.
I had it on 2nd tab - Other Software on first line, not on first tab Ubuntu software.