Have you been visiting the US at least every 6 months? If it looks like you are just doing that to try to maintain your status you might actually lose it due to abandonment since in the 2 years if you will have only been in the US for a few weeks every 6 months, it is pretty clear that you are not residing in the US. If you want to have the freedom to live abroad for a few years, you should apply for a reentry permit while you are physically present in the US. That will permit you to stay outside the US for 2 years without having to visit the US every 6 months and without jeopardizing your green card status.
Answered on Nov 30th, 2011 at 3:53 PM