In the past I have personally had issues with crashes during development, it disappeared after a while and never got the cause of it.

Today it reappeared, which frustrated me but I do believe I found the cause of it. It appears its related to anti virus software, specifically in this case avast - this is an engine problem and as such the chances of it being fixed are low, this sucks for most people (other unity games like kerbal space program have the same issue) however there does seem to be a fix for it (untested at the moment)

Most people with this issue are upgrading to their latest version of anti virus finds this fixes it.

For avast users that have this problem, people are suggesting the upgrade from avast 7 to 8 is the cause, to fix this download the latest avast, unplug your internet cable and uninstall - reboot PC - re-install latest avast.

Those with other antiviruses that experiences crashes with the game have made an exception to their AV to ignore the games made in unity.

I would like to point out and stress the point that outside of myself I have had no reports of crashes so this may be a very rare instance this occurs. For those that it does effect I apologize for any inconvenience and I hope the above goes some way to resolving the issue.

I changed my anti virus a while ago and did not link the crash to the change, im currently doing a spot of development on my laptop which again runs avast and has caused the crash for the first time in several months, this has been a big issue for me as I have spent considerable time investigating and researching the issue in the past. hopefully armed with this information it will not be an issue anymore.

With all of this in mind this is not the only reason for crashes to occur, if you do experience a crash please feel free to add it to the bug report system and try the above fix at the same time, if you stop experiencing the crash it would be helpful if you could update your bug to reflect that the above (or similar anti virus related fixes) actually fixes the issue, this will then in turn give a good indication if there are any other reasons for this kind of crash.