Surface Book 3 Randomly Freezing

I had the exact same issue. I'm not very technical. I spoke to someone in my company tech support who talked me through this.

This was solved for me by deleting all all temp files ,%temp%,prefetch files  as well as all Internet history files etc. And then a reboot. 

Since the 2004 update my Surface Laptop 3 would freeze at least twice a day. Since clearing all the files on Tuesday it's not frozen once.

I have a Surface Pro 7 and I also had the issue with the screen randomly changing its brightness. It´s caused by an energy saving feature of the integrated Intel graphics. I use my SP7 for writing so this was really annoying to me. 

What fixed it for me was downloading the "Intel Graphics Control Room" app from the store. Once downloaded go to "System" at the left of the screen and then "Energy" at the top of the screen in the center. Once there you´ll see a bunch of battery information and some toggle buttons. One button is named "Adaptive Screen brightness". Turn it off. For me it was enabled by default. Turning this off instantly fixed the issue. Sometimes the screen still randomly changed its brightness (at least in my case). If/when this happens just open the mentioned app, go to this setting and toggle the button from off to on and then off again. For me this only happened after a reboot if I remember correctly.

After a while this stopped happening completely and auto brightness just stayed "truly" disabled. This is actually not caused by Microsoft, but rather the Intel drivers. There is also a way to do this in the registry but I´d personally prefer the "official" way of doing it. I can´t remember if I actually did this fix in the registry or if it stopped "re-enabling" itself on its own anymore. But the Intel App definitely works.

I´m having the same freezing issue on my Dell XPS 15 9550 but I can´t help you there since I don´t know what´s causing it either.

I had the same problem and sent it back for repair a month ago. Still no news from Microsoft. I'm getting really upset with all this, specially considering the price range.

Got the same issue, for me, the issue occurs less often when I completely turn off Bluetooth. But still happens once or twice a day. (With Bluetooth on it happens like every 5 min)