It sounds as though your installation has become corrupted ( It happens). I would suggest that you indeed perform a Uninstall/Reinstall following the procedures as you mentioned.
However I would as a second opinion, run Malwarebytes Anti-Malware (Free) followed up by running Malwarebytes AdwCleaner to make certain you have anything untoward on your system before doing so.
These superb applications and more can be obtained here;Anti-Spyware/Malware & Hijacker Tools
Please apprise us of your outcome..
All the Best,
I might add that there is no need to be concerned in regards to your additional devices, as you have *Unlimited* numbers of devices to protect,as long as you have a active subscribed subscription.
I hope this helped..