Why render crashes? Strange cause discovered

[madrabbit]

Ok, I've found something strange and I want to share with everyone. It's possible that someone experienced this in the past and has no clue what happend, but maybe someone knows more about it and can explain better (and in more details) than me.

So does anyone experienced this thing, when max out of the blue starts to work a lot slower, even though you haven't added more objects in the scene or complex materials, or when everything was just fine a minute ago and now you can't render what you created because max crashes all the time you try it? I've found what caused it and I was absolutely surprised. Looks like it happend when I accidentally pressed

 

I have no suggestion on how to correct it. I tried to experiment with it but no such luck. So if anyone knows the reason behind it - share with everyone. I believe someone will appreciate it.