Yes, I used Migration Assistant to go from my old Mini to the new one. I don't recall the exact step by step but I printed out some information from MacWorld web site and followed it as far as I can remember.
All extensions up today and get the same message if all extensions are turned off.
All Internet Plug-ins are dated 2014.
Would deleting Safari and all associated files, restarting my Mini and downloading a new copy of Safari possibly correct this? Hadn't thought of this until this evening.
I don't thing Safari is any longer available as a separate download. You best bet would be to boot from the Recovery drive (Boot while holding ⌘R) then reinstall OS X. Whether that will cure your problem or not is unknown, but it cannot hurt. Mavericks is already out of date so it would not be amiss to go to the App Store and download and install Yosemite as long as you are doing a reinstallation. The upgrade is free.
