You could launch the Activity Monitor, set it for all processes, and see what might be hanging up. In that app, you can select the hanger, click Quit Process, and either Quit or Force Quit it. That said, however, it appears you have major system problems which need attending to. First backup your machine to an external HD. I suggest a bootable backup/clone, using Carbon Copy Cloner, SuperDuper!, etc. Then, boot with the install disk and run Disk Utility, repairing the disk and permissioins, and the Apple Hardware Test using the extended tests. If the disk passes those, boot back into the machine and see if the SBBOD problem's gone. If not, create a new admin user account, log into it, and check again. If gone, your original accounts corrupted—long an painful process to rectify. If not, then reinstall the latest COMBO update. If that doesn't fix things, then an Archive & Install, saving user and network settings, installation is in order.