Unity doesn't show login screen after startup

Unity 5.3.4 starts normaly until the project select screen where it shows this weird letters. I already tried reinstalling Unity.

When I start Unity from the command line it opens the project normaly:
c:\Program Files (x86)\Unity5\Editor>Unity.exe -projectPath “C:\Users\Robin\Documents\Unity\RandomTerrain”

I solved my problem by deleting the entire Unity data folder in AppData\Roaming