I am in the N400 Naturalization processing. I got my I-751 two years ago. I got the Notice of renewal for 1 year , but it went out of date Feb 2004. I traveled abroad to visit family last year and got stamp in passport. But my Green Card show expiration date - out of date. I don't want to be a source of bother to DHS. Did they not issue another CR Green Card extension because I am in N400 processing and if it is granted I won't need a Green Card? Or, do I have a problem with Green Card showing an out of date expiration? What should I do?

you get one year extension letter once only when you initially apply for I -751... after that you every time unless you get an approval you have to go to your local district office to get an I 551 stamp in your passport... USCIS will not send you any intermediate green card or extension letter anymore...so if your extension has been expired ... go to your local office and get I 551 stamp...good luck...Pasha

A green card is automatically extended until it is adjudicated if the I-751 is properly filed. There is no need to obtain stamps in the passport unless needed for travel or employment reasons.

An expired I-551 is an acceptable boarding document (whether one has the NOA extension letter or not).