Please tell me, when you restored your laptop to factory settings, did you then have a few hundred up-dates to be installed.
A few months back I took a Dell Laptop back to factory settings to pass-on a clean machine to a niece. It was equipped with Windows Vista and it took me a few evenings to load all the up-dates which had been issued from the date of the laptops 1st 'commissioning'. ( Over two hundred )
It's purely my opinion that, if you didn't have loads and loads of updates to install when you factory re-set and now are Not getting any, there is a real problem with the Operating System on the laptop. Unfortunately, for the moment I am unable to think of a possible answer to correct matters.
Al.