What do you mean by subtotal lines? Is this the underline show under the amount? Or is it the entire line itself?First see if the line is shown on the screen. If necessary, turn off the grid lines(View|Grid) to see the underline shown on the screen in the grid.
Second, see the report in Preview mode at 100%. When not in 100% then not all of the pixels from the page will be displayed.
Third, try printing just the second page by selecting print and select (.) Pages and enter From 2 and To 2.
If it is still a problem then try it with different reports and with different sets of data such as the Sample data. If it still occurs please let us know.