I've had this problem before too. Teddy has the right idea--the data on your report is probably spilling over into the margin areas, which ends up being printed on a new page.
In my instance, one of the text boxes on the right edge of the report was too long. It was sticking out into the right margin of the report and the extra page was blank because the text box wasn't completely populated.
Check to see if any of your fields are beyond the printable area of your page layout.
Good luck!
KerryL