Confirming the security error…
I use the plugin on a multisite (Yes, it works like a charm, Chris, tnx!). First I saw “Security Error” at the bottom of the “At Glance” widget in the dashboard of the main site. The <div class="sub"></div>
had disappeared too, or at least that section was not styled.
I just updated a bunch of plugins and didn’t have time to look for the cause. Then I created a new site as a new user to test something and none of the admin screens were available in the new site…
Then I found this topic, deactivated Better YOURLS: problem solved.
Activating the plugin again, however, and creating another site, does not reproduce this error.
Moongear, I don’t think it’s ok to resolve the error like this. You basically interrupt the validation, so yeh, it does not die. Yet I would assume it is not what causes the error, especially since the same method, with OR, can also be found in the codex.