Second MacBook Air - random restarts and shut-downs, failing to sleep

[cleanup]

First MBA was a refurb. Worked great for about a month; shipped with 10.8.4 but updated to 10.9.1 then 10.9.2. The laptop would randomly shut down when I put it to sleep (regardless of closing the lid or choosing Sleep in Apple Menu) so that when I re-opened it, it was off, and had to use power button to reboot (it would load all my apps again but it was a full boot complete with startup chime despite volume being muted before). Problem persisted through numerous PRAM and SMC resets. Then started having very odd audio problems (would warble, lag, become staticky and unusable). Returned/shipped back to Apple and bought a retail (new) unit at the Apple Store instead.

Just now, I was literally just sitting there, talking on my phone, staring at my computer screen, when suddenly the screen goes black.

Laptop would not respond to lid opening/closing or even power-button. Had to hold command, option, P, R, then power button to even get the computer to boot. Similarly, it loaded my apps again upon booting but it was a full boot complete with start-up chime.

What on earth is going on? I'm about to return this one and switch back to a Thinkpad.

Is it Mavericks? Random shut-downs and reboots seem to be abound on the internet with Mavericks. Should I roll back to Mountain Lion?

I'm getting exceptionally frustrated; this is literally about the worst problem a computer can have, especially a work computer; it is simply not stable or reliable in the least.

Is there any way I can find crash logs or error logs? Or run diagnostic/hardware tests on my own without having to bring it into the "Genius" (read: hipster idiot) Bar?

Any advice appreciated.

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Also, the most recent crash (new MBA), it didn't have any peripherals or even the adapter plugged in. Was at 98-99% battery.

Just installed the SMC update.

 

[bigjnyc]

Same thing is happening with my girlfriend's MBA, it just randomly shuts off and then it takes a while of pressing the power button for it to turn back on..... I brought it in to work with me today so I can take it to the Apple store. I have a genius appointment at 12. I'll let you know what they tell me


*UPDATE*

So I took it in and they didnt find any hardware issues when they ran the diagnostics. But since its under warranty the genius said they would replace the logic board and repartition the SSD. So I have to pick it up in 3 days.

 

[iCheddar]

It's gotta be Mavericks. I haven't seen anything official down the pipeline, but in my small shop I've seen two MBAs in with these issues, and didn't see it until AFTER 10.9 came out.

Also, one of the MBAs I swapped the MLB twice. Did it once, did it again a month later with similar, but different symptoms.

 

[mmomega]

So you're experiencing problems on a beta OS? 10.9.2 has known issues on some MBA hardware, it's on the dev forums i.e.: FaceTime camera won't work, won't wake from sleep w/o hard restart.
Running important work related material on pre-release software is asking for trouble IMHO. Go back to 10.8.4 or 10.9.1 your hipster bar won't be able to help you much with software they aren't trained to troubleshoot.
Also which build of 10.9.2 are you currently running?