I renamed HKEY_LOCAL_MACHINE\SOFTWARE|Microsoft\Windows Search\FileChangeClientConfigs so that if needed I could restore it. Then I restarted my PC.
I had the same issues described by others: indexing was not working, I could not start the service, Windows Resource Protect found corrupt files but could not fix them, etc. I tried Barry's solution of renaming a Registry key and viola! after I rebooted
indexing was working again in both Windows and Outlook. The indices had to be rebuilt but now everything is back to normal.
By the way, in my case the Registry key did not point to SkyDrive - it simply had no value. However, renaming the key solved all of my problems. Thanks, Barry.