LoL Client causes entire laptop to freeze and need force restart

Win 8.1, this has begun happening since Fiora patch only, eight times since last Friday across 3 accounts. Maybe it was after the Fiora patch, the much smaller one? I've tested this with just the client open after a fresh restart.. it randomly happened 10 seconds in, it's happened 15 minutes in to the client being open after my laptop's been on for five hours. It's happened when I've been tabbed out browsing the web, when I've been in TeamSpeak, during a Skype call, etc.

This has happened across 3 accounts at different windows of the client from Champ select in normals/ranked, to looking at champs to buy, and so on. I have tried Win 7 Compatibility mode, Run as Admin, etc. I will try to uninstall/reinstall, but beyond that, I am out of ideas on what to do. I've been able to do everything else freeze-free, so I'm isolated it to LoL. My Windows Event Viewer is of no help and does not notate anything beyond the hard power off/did-not-shut-down-properly-restart warning message.

Thoughts?

Also, completely UNRELATED and more in-game with Devourer: If your team kills Dragon and you've been killed before dragon dies, even if you get assist acknowledgement, you do not get the stacks. This might be working-as-intended, but if I die and players die afterwards, I get assist-points towards Sated, so just curious. =)