Problem with

I've installed freebsd 7.1 on a compaq presario 700 laptop with a savage graphic card. Savage driver doesn't work so i use vesa driver, but when i run "startx" i can't switch to ttys and i can't run "shutdown". When i try, the machine go in a strange state: black screen, no ssh connection, doesn't respond to ping etc.. every time i must halt it by pressing power button. Help me please! thank you
It's not enough information.
Look /var/log/Xorg.0.log for errors and warnnings. Try to remove ~.xinitrc, /etc/X11/xorg.conf and then startx. And again look /var/log/Xorg.0.log for errors. Try to Xorg -probeonly.