Attached Link: http://www.corel.com/support/downloads/index.htm

Is this bryce 5? if so, if you enter the terrain editor and make a change here and there, sometimes the editor will add a line of pixels at the top. This is a bug supposedly fixed with the patch. Take a look at the terrain in there, and see if theres that white line at the top. If there is, it's been fruitless for me to try and erase it, so I have to start a new terrain.