You need to check all your objects on the report. If they have the "can increase to accomodate contents" property checked or if something you did in report design caused them to expand, then you'll never know it just by checking your margins and your page size, because it doesn't reflect there.
The only option is to literally go into the Report Designer and see, by the ruler tool on the top, how wide and long your report is. I'd advise resizing all your tables/textboxes/matrices/etc. width wise first, then height wise second. After that, resize the body so it is the same size as what the report properties thinks it is.
I also recommend turning off the "can increase" property for each object unless you really really need it on.
Catadmin - MCDBA, MCSA
"If a person is Microsoft Certified, does that mean that Microsoft pays the bills for the funny white jackets that tie in the back???