Update ..
I have to say it isn't WHAT you know, it is WHO you know.
I swear, our application was submitted in January 2010, transferred in February, and then ended up in the dead letter bin. I FINALLY called Congressman in October .. and BAM .. things started moving ...
Then this no green card after approval issue came up ..... so I called someone I know with ties to Hameland Security and he called local USCIS office and he got me in for an appointment with out using Infopass.
We got our I-551 stamp today. WHEW!!
I HIGHLY recommend that you call people in high places if you get frustrated with your case and have due cause!!!!