Safe mode level1?

I have had a master/slave setup using ADAT for a while now and noticed when i do any kind of recording everything is fine. When i browse the web, any kind of audio or video streaming, I have to set my driver setting to safe mode level 1 to hear any audio.This includes just playing files off of my pc as well. My questions are.

What is safe level and what does it do.
Should i just leave it at safe level 1 or will effect other things like video editing etc.

Another thing is when i switch to ADAT from my internal source, my bit rate goes from 44100 to 44082. It has not given me any problems so far but just curious (bad cable???).

Thanks