Autoscroll bug Rated 3 out of 5 stars

The dragging of links work fine, but this introduced a problem elsewhere:

When clicking on the scrollwheel on a page (pointer forms an autoscroll icon) and then I move the pointer anywhere to the left and click my scrollwheel again to cancel autoscroll Firefox will go back a page. Don't think this is supposed to be happening.

Have disabled it for now as this keeps happening too much. Using Firefox 4 Final, Windows 7 x64