HELP Restoring an Exchange Mailbox - Access is Denied

Hello

i am running a windows server 2003 with backup exec 10D installed, with Exchange server 2003

i am trying to restore a mailbox of a former employee who may have some important emails we need, when i try to restore i get the error access is denied

things i have tried with no luck:

1. re-create the users account and mailbox manually

2. restore to file

3. turned off on access scanning on the sophos anti virus

anyone who may have some knowledge on please get in touch

Thanks

Kev