Plugin generates "Cannot modify header" errors, renders wp-admin inoperable

Dear SiteBrains team,
I came across your plugin recently (via a Quora post, actually), and decided to try it out.
I installed SiteBrains plugin version 6.2.1 (I’m running WordPress version 3.2.1). It installed and activated seemingly without trouble, however, when I go to perform pretty much any administrative action (save a settings, moderate a comment), I get a blank page and the same error as in this post: https://www.ads-software.com/support/topic/i-cant-log-in-to-wp-admin
Specifically,
"Warning: Cannot modify header information - headers already sent by (output started at /*my site*/public_html/wp-content/plugins/sitebrains-1/Index.php:1) in /*my site*/public_html/wp-includes/pluggable.php on line 934"

Disabling your plugin fixed the errors, but I would certainly like to give it another try, if fixed.

Some more details:
To see if any of my plugins are interfering with SiteBrains, I deactivated all my other plugins and re-Activated SiteBrains. Incidentally, during re-activation, I got the following warning from WordPress:
The plugin generated 3 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.

Anyways, the same error was generated even when SiteBrains was the only active error.

I’m happy to provide any other diagnostics info.