my roomate GC stopped for 1.5 years at FBC name check.
in Jan 2005 lawyer suggest contact senator to check it. he wrote a letter in his employer's name to local US congressman(house, not senator). after 3 weeks the secretary of congressman replied that he cannot interfere with FBI name checking. but about 2 weeks later, he got a call from his lawyer that he received the I485 approval notice. it is end of Feb 2005.
that is the magic of congressmane!!!!!!