Don't be tempted to change your Google account from an @googlemail.com account to an @gmail.com account even if google advise you to. If you do, it will break your accounts on your phone like Talk, Market and so on. It is likely that you may have to factory-reset your phone to fix this.
At the moment, the resolution for this is a factory reset of your phone or restoring your account back to @googlemail.com, so be warned before modifying your account!
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