kinda urgent: my computer at startup would at times crash many times and the last time I was on my computer I used 3dgamestdio A5 and I made a huge outdoor level and when I run it my computer would crash. would that really damage my computer?

And also how can I limite the cameras range on view so that like after like 50 yeard's or so that it won't load or would be blury? any idea's?

Thanks for your time.