I've had about 10 subpages disappear which were previously doing quite well. Most were at #1. They have been replaced by the homepage 2 -5 positions lower. I went and checked all the backlinks and all linking pages except one have a greyed-out toolbar. The one that didn't have greyed-out TBPR was for an extremely popular title with over 80 links on the page.
Quite possibly this has contributed as well. I have a lot of links like this.