is now in
And my template problem is solved
renamed ~/.libreoffice and ~/.config/libreoffice
and started libreoffice again.
copied templates in the now new ~/.config/libreoffice
And I'm happy again, I think there was a wrong rw permission somewhere.
After all this fiddling I cannot reproduce the error annymore.
Tried 3 times, with LXDE on Celeron800 and 3 times with KDE on Q6600, installed new LibreOffice with the changed lomanager without errors
So on my box, version 3.5 it is.