I have about 15 new iPhone users. All have been set up in Exchange 2010 to allow active sync. Most work fine, but I have one 3 or 4 users who lock the active directory password on them every 12 to 24 hours. The phone will all of a sudden start popping up a message stating "Wrong Exchange Password" . All settings look same . Any ideas? They have brand new Iphone 4S with 5.1 on it.