Important
i moved from company A to company B after i received my reciept of application from INS

.
while i was with B and before i received the approval for B (delayed due to security check ) MY OLD Company A notified INS that i have left for company B.
I joined company C next the next year after filing and receiving the receipt from INS..
at that time the application for B was PENDING in security check.
i received my approval of COMPANY C even though my application for company B is still pending ( to this day ). INS in a decision said that because COMPANY A "withdrew" the H1B while my COMPANY B application was "pending " i was out of status.
since then i have left the country and applied from canada
MORAL : make sure your chain of events is not broken .
ofcourse if you ur muslim this does not apply to you.