I have the same issue, its maddening, really is, and when I do what you recommend-all I get is the little blue circle and nothing happens! Its freezing no matter what and all I get done is one or maybe three photos! UGH! I would appreciate another suggestion! THANKS!
If turning off GPU acceleration in Lightroom doesn't work, there are instructions further down on that webpage telling you how to disable GPU acceleration manually. Have you tried that? The symptoms you are describing are very common for many graphics cards. You need to try to resolve that issue first. If disabling GPU acceleration manually doesn't help, then come back and maybe we can come up with some other suggestions.
If you can't get into preferences, thry this solution:
Close Lightroom. With Windows Explorer, navigate to C:\Users\[your username]\AppData\Roaming\Adobe\Lightroom\Preferences
Open the file Lightroom 6 Preferences.agprefs in a text editor, like Notepad.
Very close to the end of the file there is a line that says useAutoBahn = true, - change this to useAutoBahn = false,
Save and close the file. Now try to start Lightroom.