The renaming of the Config file worked for me.
I was having the same problems as others in this thread. Searching my PC and the messages I could see that the problem was that my index file itself was corrupted or damaged so that the SEARCH would not start. Since it would not start, I had the Advanced Options greyed out and hence could not change the current search location. By renaming the registry file and effectively hiding it from the operating system, the search started and I could name a new location. Now the PC is rebuilding the index at a new location that I can examine. I hope my PC does not have a relapse!