What stage does it get to in the activation process? Does the handset say:
or does it get to the:
Waiting for Services
If it doesn't get to the second stage and just sits there on "activating":
1. Check with Vodafone that BES is enabled on the SIM card
2. Have a look in the user's mailbox for a message from @blackberry.net with an ETP.DAT attachment
If #1 is okay and #2 never arrives, then I suspect a spam or virus scanner is probably preventing the ETP.DAT message from getting through, so disable any temporarily and see if it helps.
Oh and activate the handset with the address that the BES reckons is the right one - you can always change it later when the mailboxes are enumerated properly.