We'd really need to see small demo to give an exact answer but the question is "why are you absolutely placing the div?" and to what effect?
Absolute elements are removed from the flow and so they care nothing about what went before and if stuff is in the way they will just overlap.
You can tie the absolute element to the parent div by adding position:relative to the parent but this still won't stop the absolute element sitting on content should content get in the way.
If you are just trying to place a fixed height element at the bottom of a div then you would need to add the same amount of padding to the bottom of the parent so that the absolute element sits in a protected space. However you can't do the same thing if you are placing the absolute element in the middle of a div vertically because there is no way to protect it.
What is the absolute div for? Why not use a non positioned element and just let it go with the flow.
We really need to have a bit more information before we can give a specific answer but usually when we see absolute positioning used it is used for the wrong reasons.:)