To get an absolute path we will add the site http manually.
Open the fck_image.js which is located under HTMLEditor/dialog/fck_image, and on line 434 change it from:
GetE('txtUrl').value = url ;
GetE('txtUrl').value = "http://localhost" + url ;
You will just need to replace "http://localhost" with your absolute path.
This is a temporarily work around and i will keep looking to see if there is a better work around.
Let me know if you have any other questions.