Moreover, I found what happened to me and have the solution.
Since I am newbie, I installed nvidia drivers from safemode, which makes something (defvb?) not to be loaded. I have understood how to turn off X (by run /sbin/init 3 as root from a terminal (ctrl-alt-f1 and log in as root)) and will do it now. Then I will reinstalla the driver and everything should be perfectly working. In case nvidia still won't load automatically, since I have Mandrake 9.1, I will "nvidia" to /etc/modules
I should have understood almost everything. Please confirm.