Ok i rebooted and got one more time this problem
I tried doing
and it printed nothing, and when i tried startx i had the same error
I also tried adding the line your mentionning
alias char-major-195 nvidia
in modprobe.conf, but again there was no change ...
so i reinstalled the drivers lol
anyway, the installer says something about "tainted"
i dont know what it means, but maybe ther can be a relation?