I don't know exactly what caused the current behavior: i cannot boot into cinnamon anymore.
How to reproduce:
1. LMDE, (dist-upgrade performed), 64bit
2. Boot LMDE
3. Login to a cinnamon session
4. I then get a black, very reduced interface with no menu, no windows boarders etc.
After that I can open a terminal and start cinnamon manually - then every thing works as normal.
Ho do I get automatic startup of cinnamon back again?
Thank you for any hint on this subject.