So I am working on a friends DX and over the past few days her Exchange account has stopped working. At first she would still be able to receive emails, but not send them. Her calendar would also not sync. We tried removing the account and beginning from new but now it won't link at all. The phone will not recognize certificates and still will not connect when the validate certificate option is unchecked. And again the phone is still running 2.1 and has not done the over the air update.