Pop Over Plugin problem

When I hit 'Update' button I get redirected:

1. To the log-in page of one of my sites (user site)
2. To the main site's dashbord (after I deactivated that site from above)

Also, plugin's text field does not save information bellow:

<a href="http://site.com/something/"><img class="alignleft size-full wp-image-2185" title="need_portfolio" src="http://site.com/files/2011/02/image.jpg" alt="" width="500" height="200" /></a>

Even if I don't put any code in text area same thing happens.

Maybe I should mention that site from 1. was actually a members site with BuddyPress plugin activated. But I had many upgrades since then. And I doubt that it has anything to do with this cause I still get redirected to the main site's dashboard.