I am very new to linux/backtrack. I recently tried to download the .iso of backtrack 4, and I used unetbootin just as this site recommended to install on usb drive. All seemed to work, but when I type: startx and press enter, a whole bunch of stuff pops up like

(EE) Screen(s) found, but none have a usable configuration.

Fatal server error:
no screens found
giving up.
xinit: Connection refused (errno 111): unable to connect to X server
xinit: No such process (errno 3): Server error.