516639 Printing problem

We have problem with printing receipts from our admin area. When we print receipts to normal A4 paper on lazer or office jet printer then it works fine. When we print to a dot matrix printer then the problem comes in. It prints a horizontal line right at the top and again right at the bottom. These horizontal lines don't print on the other printers. At first we used an active x thing that needed to be installed or downloaded from some site. The last coder changed the printing to normal javascript code.