iPad Mail Troubles - Saved Drafts Disappear, Sent Mail Doesn't Show

I'm having several iPad Mail problems, but they don't happen all the time...
I have finished emails that I want to save as a Draft, I hit Cancel, then Save, and the email appears for a moment in the Drafts folder, then disappears. I can't find it anywhere. And the messages were not in the Trash or Deleted Messages folders nor in any MobileMe folders... just gone. Very frustrating, especially with one very long work-in-progress email.
I have sent several emails from iPad Mail, hear the "swoosh" sound, and there is no trace of them in the Sent or Sent Messages folder and no BCC copy comes through, nor do they appear in MobileMe, but I have confirmed with intended recipients and they did receive the emails. This is not good.
Even more frustrating is the fact these problems only occur sometimes, not all the time. And I can't find anything consistent or make the problems repeat by doing something specific.
Right now I've had to stop using the iPad for any important emails. Any clues on these issues?