DNG and RAW problem.

To be honest, I do not wish to work with DNG files, but for some reason there is a setting on my system that is converting the files to DNG and I am not able to find that setting to turn it off.  I am wondering if someone has any idea of what I may have done to turn this setting on so that I could turn this setting off.  Could there be some setting in Lightroom 4 that I may have unknowingly set and is causing me the problem of changing all of my raw files to DNG files?