I've used Tinytip for quite some time, I was getting this problem then and continue to get this problem with Cowtip as you can see in the following screenshot:
This problem only occurs when I try to anchor the tooltip anywhere except on the cursor..I will scroll over something and get a huge tooltip that takes up the entire right side of my screen. It doesn't always happen, sometimes it anchors appropriately, while other times that will happen.
Can someone enlighten me on what may be causing this? I can provide a add on list if it's neccesary.