"create mail for exchange profile to send emails" error

Why why why do I get this on both my nokia n85 and e90 with Mail for Exchange? It just seems to happen! Very frustrating as I then have to either reset the phone which DOESN'T always work :( Having it just happen to me again, a reboot of the phone worked to retrieve emails but now I'm getting the message again and can't even go in to edit the settings (nothing loads and the phones pause for a short while). Very disappointing...