i filled i485 and i765 applications last november 2006 and did my biometrics last december 2006 and then uscis sent me a letter asking for more evidence concerning my affidavit of support .so i replied with a joint sponsor application ,the joint sponsor application was recieved by uscis last january 31st and since then . i didnot get my work authorization .and my case is still bending , i never been called for an interview and after alot of visits through infopass and calling customer service and submitting 5 service requests .i got one letter from uscis that my case was pending and that i have to wait another 6 months to get a decision concerning my i 765 application .so i talked to the congressman and his immigration assistant replied that they are performing a back ground check .and that i have to wait another 60 days .she said that she was surprised because they start the back ground check even befor they send me the work authorization ,and the nbc representative said that this is the new policy that they perform the bck ground check even befor they send u the work authorization ,now am just waiting .very dispered and hopless .so i realy don't know what to do especially that the uscis committed in their last letter to me that these back ground checks are a part of the case for any one applying for such immigration benefits ...please advice ....what is the expected time limit for a back ground check ...and what if i didnot get any reply with in the comming 6 months and what if i get a lawyer .will that make a difference .thanks