When you print a user manual Help+Manual first generates a PDF file and then prints it. The PDF is generated using a printer driver and "optimized" drivers from printer manufacturers can sometimes cause output problems. The printer driver used to generate the PDF is normally your default printer driver but it is possible to select a different driver for PDF generation if necessary.
You can generally solve this problem by installing a different printer driver and selecting it as the reference driver for PDF generation. This driver does not have to be for a printer that is physically connected to your computer. In fact, you will probably achieve the best results with a standard printer driver from the Windows CD rather than with an "optimized" driver from a printer manufacturer.