Firefox 4 Tor Browser Bundle does not start on CentOS 5.6 (64Bit)

I tested the recent TBB [1] on CentOS 5.6:

./start-tor-browser ./start-tor-browser: line 53: pidof: command not found ./start-tor-browser: line 53: pidof: command not found

Launching Tor Browser Bundle for Linux in /home/ca/tor-browser_en-US

(:3800): GLib-GObject-WARNING **: IA__g_object_set_valist: object class GtkMenuItem' has no property named label'

(:3800): GLib-GObject-WARNING **: IA__g_object_set_valist: object class GtkCheckMenuItem' has no property named label' Qt: Session management error: Authentication Rejected, reason : None of the authentication protocols specified are supported and host-based authentication failed

Exited cleanly. Goodbye.

[1] https://www.torproject.org/dist/torbrowser/linux/tor-browser-gnu-linux-x86_64-2.2.23-1-alpha-en-US.tar.gz