iPod Mail.app problem and solution

While the upgrade to 2.0.1 firmware on my iPod Touch went smoothly and appeared to be working fine, I later discovered a problem with the Mail.app. Since upgrading the firmware erases the installed OS, it also removes the mail messages. As I use Gmail with IMAP access these messages are stored in the Gmail account so should be synchronised when accessing the Mail application. What was happening was two attempts at downloading the mail messages then Mail.app quit.