Also, if you have not already, try cleaning out the inside of the scanner. These lines may be related to dust on the mirror, which creates interference. This is consistent with the lines running parallel to the sensor. And check your cables. It is possible that data is not being received properly and/or assembled correctly once it leaves the scanner. In my case, once I cleaned out the scanner, and replaced my G3 (bad power supply), most of these lines disappeared.
One other possibility rests with the white strip. Have you checked yours for dirt?