I recently upgraded our Exchange server to 2003. I'm running the desktop redirector to forward messages to my handheld. Since the upgrade every message that comes to the handheld and I reply to gets a red X saying the Mailbox couldn't find original message, if you are forwarding or replying please resend the message. If I resend it goes out fine.
If I send a new message right from the BB they send the first try, just problems replying and forwarding. Thanks for any help.

are you removing or moving the message from the outlook inbox? this only happens to me if i have either deleted the email from my inbox or moved it to my PST archive (and it remains on my handheld), then try and reply to it later on from the blackberry.

No, it happens with the e-mails still in my inbox in Outlook. I'm not using a PST file, just the mailbox from Exchange.