There is more than one registry attribute that needs to be changed. You have likely gotten them “out of whack.”
Use POSH, GmbH’s free utilities to change the registry settings whilst SketchUp is not running.
They are a German distributor for SketchUp. (@sketch3d_de, represents them here.)
Otherwise you can use the batch
files I posed:
For SketchUp 2016:
[Win] Setting Preferences > OpenGL switches off via batch script - #6 by DanRathbun
For SketchUp 2015: