I tried the PL, BP, and WP updates and no better. :-(
I disabled almost everything, like I said before, and then I switched themes to see if it's PL or BP/WP and I got a WP_DEBUG error so I went to disable the BP for PL plugin (while Twenty Twelve was active) and the screen went white/blank except for this error:
Notice: Use of undefined constant CORE_VERSION - assumed 'CORE_VERSION' in /wp-content/plugins/pagelines-buddypress/pagelines-buddypress.php on line 67
Fatal error: Call to undefined function toggle_integration() in /wp-content/plugins/pagelines-buddypress/pagelines-buddypress.phpon line 57
So it wouldn't let me deactivate that plugin without activating PL then deactivating, then switching from PL.
Other than that, it's not a PL issue, unfortunately... I'll keep investigating on my own.