Office 2007 Chaning default printer

I am using Office 2007 on a few vista machines and some xp machines. If my default printer is set to printer 1 and i print to printer 2 a few times in a row it changes the default to printer 2. I have this problem personally using access(Vista)and a couple other people using word(XP machines). We never had this problem in Office XP. Thanks in advance