What operating system?
What exact version number of Lightroom 6 do you have?
OS X Yosemite, version 10.10.5. As far as lightroom CS6 is all I know
Well, I would suggest you install Lightroom 6.3
(which of course will be a total waste of time if you already have installed Lightroom 6.3)
It wasn't the same light room i have, mine had 800 and something MB, this had 224. I downloaded it anyway. Same result, except it stayed in my task bar for a about 5 seconds then dissapeared. More than it did before.