I am having the same problem. Version 2.0.5 (if I remember correctly) on Mint 18. No error messages or anything like that, and I ran system monitor to see if maybe memory was being filled up, nothing. The software literally just shuts down and goes back to my desktop. The printer will then reboot and just sits there. Again no errors or anything. I did try running the printer on a spare power supply just to make sure it wasn't something there, same problem. I plan to try a print off the sd card to verify that it is a computer/Repetier issue. The last time this happened (last night) it stuck the nozzle in the part, cooled, then when I tried to home, actually broke the nozzle... As soon as the new ones arrive I will confirm. Printer is an Anet A8, all less than a week old, and the install was a second one as I was thinking maybe I had a bad download the first time, clearly not.
I will also try server and see what that does. It's too bad, other than that for a new machine with little tuning, the prints look really good, if only they would finish.
One final note, this seems to happen randomly. Some prints will go for an hour then die others after 5-10 minutes. Does not seem to be any common factor that I have found yet.