When I print to my inkjet printer, there is a line that runs across my paper. This occurs when the printhead or something on the printhead is too close to the paper. Keep in mind that the ink is still wet whenever the paper comes out of the printer, so if anything rubs against the paper in the process of printing, the ink will smear or look like a line across the paper. To correct this, check the thickness of the paper. If it is too thick, the head will rub on the paper causing the problem.
Some printers have an adjustment for the head.
Try backing this adjustment back away from the paper. You may also need to use a lighter weight paper. Ink may also build up on the bottom of the head, creating a bump on the head. This bump may rub on the paper and cause the lines. This may be fixed by cleaning the printhead.