Found a fix. I'm not sure exactly what caused it, but what I did was deleted the Arma 3 Alpha folder from user\Documents\Arma 3 Alpha , also user\Documents\Arma 3 and finally user\AppData\Local\Arma 3. I was able to play without problem. Bare in mind, I only tested this once.

Update: Scrap that, it seemed to temporarily fixed the problem, but it is crashing still.

https://dl.dropboxusercontent.com/u/83732555/Arma%203%20crash%20reports.rar

Here's what you asked for.

Even though I don't have any problems with motion blur etc. I'll still support this for the people who do.

You're saying it won't let you copy and paste playable units, other than non-playable?

Or it's the server you're playing on... Have you tried multiple times on different servers? Also are theses server actually people computer's because I've seen a lot of them running on their PC's.

Edit: it may be due to you having people join you since you're hosting it on your PC

I've had a similar problem when dying and switching to another playable unit and this happens.

Disable Hyperthreading on your CPU. It can cause performance issues.

Yep, I had the same problem.