When Landsat7 images are used for analysis work (e.g. calculating NDVI) these strips are very troublesome. If there is a method to correct this effect please do let us know.
You can use gapfill.tbx (toolbox) in ArcGis Geoprocessing we can help you if you send me a message in my email : [email protected].
It's a several ways to do this untill the black line was erased definitivelly. you have the videos gapfill with idrisi, envi and arcgis on line in youtube.com.