Black screen when open Time Machine on Yosemite I use a 13 Macbook with a thunderbolt display on Yosemite. Since the installation of last osx version, if I try to open Time Machine I can only see a completely black screen on laptop screen. The other screen remains with previously opened windows. So, time machine is completely unusable. I can only use ESC to exit.

Any ideas of what can be happening here?

If I don't connect my second monitor, works fine.

This is my displays configuration:
If you have this issue using Yosemite, i found a turn around:


Go to Preferences - Mission Control
Uncheck "Displays have separate Spaces"
logout and login


This will fix Time Machine to display black screen in one monitor. The side effect of this is you loose the abilitty to use monitors as separate spaces but isn't that bad.