Hey @gnomerchaun, welcome to Discussions! I'm sorry to hear you've run into this issue, and that it's crashing your entire system.
I see you've already reinstalled the game, but have you reinstalled Ubisoft Connect as well? If not, you can find steps to do that in this FAQ. Ubisoft Connect is in charge of synchronizing achievements, so it could be an issue with the program rather than the game.
Please also go ahead and complete the other steps in our ...