I just upgraded WordPress to 3.4.2 and the entire site was no longer accessible. I was presented with a blank screen with one word:
I could not access the control panel. I started up phpMyAdmin and went to the wp_options table, and found active_plugins, and deleted the contents (after first backing up of course). This got my site back up and let me log in.
I then activated each plugin one by one. When I got to Better WP Security the site gave me the blank page with the word error again. After cleaning out the active_plugins record via phpMyAdmin again, I continued through the process of activating plugins one by one. Every plugin worked without a hitch, except for Better WP Security.
Just to be sure, I copied the active_plugins record, then activated Better WP Security one last time. Again, I got the error. I replaced the active_plugins record with my copy and the site worked again. So the problem certainly seems to be with Better WP Security.