Lightroom 6 under Windows 7 worked ok from November 2015 until yesterday. When trying to start it today, only the start screen with the picture of the trees opened. Then the rotating mouse pointer appeared, and in the title line "Keine Rückmeldung" = no feedback. I tried to open LR with several catalogs, and also tried to create a new catalog, all with the same result. Something stops LR from continuing. How can I resolve this?
You need to turn off the Graphics Processor from the Lightroom Preferences.
Open Control Panel >> Go to Device Manager >> Under the Display Adapter look for the Graphics Adapter >> Right Click and disable.
Go to Lightroom Preferences from the Edit menu
Click on Performance tab
Uncheck the Graphics Processor
Open and check if it works fine, then go back to the Device Manager and enable the Graphics Processor.
Let us know if that helps.