10+ years of using Ubuntu and still have problems from time to time...

Yea me!!....Still in love with this distro after all these years....BUT every once in a while, I run into problems. Sometimes easy ones, sometime baffling ones; like this one:

Update-manager came up with a wierd one the other day. I'm still on 14.04 LTS, not trying to upgrade to 16.04 yet, but it's a 108MB update and it keeps asking for the 16.04LTS CD/DVD. It will not move further than that.

Has anyone else experienced this and what are my options? I'm content in waiting until stable to stable in July so upgrading is not an option right now.