Document moves when printing in Illustrator

I print a document that has even margins on both sides. No problem. If I go in to make any changes and print it out again, the document has shifted majorly to the left or to the right. It looks right viewing it put I just have to keep moving it over a little at a time until it prints out evenly again. When I make changes, I am careful not to shift the document but I'm obviously doing something wrong. It is very frustrating. Am I doing something wrong when changing the info? Thanks.