Recently we had a User state that they were having difficulty obtaining daily Updates. However after 'Updating to the latest 'Adobe Flash Player' it resolved the issue. I mention this as my Daughter called earlier and had the same issue. After making certain she had the most current Windows Updates/Internet Explorer.
I asked her to check her Adobe Flash Player Version. Sure enough it was not current, and immediately after installing the latest Version ( 184.108.40.206 ) she ran a Manual check for updates successfully. Just thought I would mention the importance of keeping (All) Add-ons/Extentions current.
To add, I advised her to set her Adobe Updating to 'Automatic'