This might be the solution. I've had this Yoga 3 Pro freezing problem for about 6 months. It's only the last month that I discerned it would freeze when the screen was moved. Apparently there's a sensor in the hinge.
I read in this thread that disabling the wifi adapter seemed to keep it from freezing so as weird as it sounded, I went into the device manager to try disabling it. Instead, before disabling it, I right-clicked to see if there was a driver update (for the Broadcom 802.11ac Network Adapter driver under Network Devices). There was an update available, which is unusual, as I don't think I've ever had it find an update through the device manager. So, I let it update over the web and it completed in about 20 seconds.
I then moved the screen again to test it, and it froze again --- just like the previous 7-10 freezes I'd just endured in the past 30 minutes, which always required a hard reboot by holding down the power button.
Seeing it didn't work, I rebooted, realizing the driver was updated but obviously not loaded until rebooted (duh). I rebooted and have not had it freeze since, even though in the past whenever I would move the screen (open or close it even a tiny bit), it would freeze. I'm swinging it forward and back full tilt now and nothing. No freezing.
Is it fixed? Seems to be but time will tell. If it lasts the week, I'll consider it a true fix and will post back here. If it turns out to be a true fix, this should be reposted on Lenovo and other forums as I've looked everywhere for a solution to this and know that many others are also trying to solve this VERY annoying problem and that Lenovo has been 100% USELESS in solving it (shame on them for their horrid support in handling this major problem). Did I mention I will never buy another Lenovo as long as I live after this? Nice going, Lenovo. Anyway, it can't hurt to at least try disabling/updating the Broadcom driver if you have this freezing issue.
I was on Windows 8.1 for the past 9 months or so, then just upgraded to Windows 10 thinking it might help fix the freezing, but it didn't help at all. As a side note, if you're on Windows 10 or thinking of upgrading, I recommend Spybot's free Anti-Beacon, which is anti-telemetry software that blocks Win 10 from calling home and wherever else and spying the crap out of you (I'm about to switch to Apple as Microsoft is being a bunch of evil nitwits with this pure spyware masquerading as an operating system).
Let me know if either disabling or updating the Broadcom 802.11ac Network Adapter driver helps anyone else. Just right click it under Network Adapters and then click "Update Driver Software" or you can try disabling it from there if no update is available. For me, it updated to version 7.35.338.0, which was released 12/10/2015, so it's a pretty recent update.
Maybe it's just a weird coincidence because who on earth would suspect that a wifi driver would have anything to do with a laptop freezing when the screen is moved/adjusted? Bizarre. But, I'm VERY happy for now. If this ends up being the fix, major props and thanks to Revihs for pointing out this apparent connection between the freezing and the wifi driver. Would not have guessed that in a million years.
GeekMan108's solution worked for me too: 2014 Lenovo Yoga 3 Pro w/ Windows 8.1. Started freezing for no apparent reason 2 months ago (Jan 2016). Performed a laptop 'refresh' - didn't solve it. Manually performed an 'update device driver' within device manager and it said I had the latest network adapter driver (Broadcom 802.11ac Network Adapter). Continued to freeze up. Decided to download the latest driver and 'force' an update for my particular OS/adapter specs. So far - it's worked. No freezing despite opening/closing laptop and moving it around repeatedly. Any other time I moved the laptop even slightly would cause it to freeze. Keeping fingers crossed for now, but my thanks too goes to this forum if this sticks as there is no way I would have ever arrived at this solution.