When yo insert an image in a BV page, you can
1. Specify a location on your computer, using the Browse feature
2. Or, type directly the image file name. If the file name is simply "image.gif" , when viewing the page on the net (the published page) the browser will look for the image file in the same directory where the page is. In BV and in preview the image will NOT appear. If, instead, you define the image location as
http://www.yourdomain.com/path/to/image.gif the browser will look for it in the specified location.
In this second case, the image will NOT appear in BV, but it will when published AND in preview
3. If your banners don't work any more, it is probably some conflict somewhere. Without seeing the code i can't know what is wrong