[gsnixon]

Ok, so I have the exact same issue with the k2 sidebar module. However, I think this means the issue somewhere in the widget plugin API.

Atsutane – I think this may be a solution for your akismet problem. Try disabling the K2 sidebar module plugin, and enabling Akismet. Does bbpress still work? If yes, comment out lines 374 to 475 of akismet.php, that is, from right before

function widget_akismet_register() {

to right after

add_action('init', 'widget_akismet_register');

This should allow you to use both plugins at the same time.

Let me know if that works.