Can't select Exchange 2007 mailboxes

BE11d 7170 running on 32-bit Server 2003

Exchange 2007 running on 64-bit Server 2003 w/ agent

 

I can back up the information stores but cannot see the individual mailboxes. I have installed the CDO on Ex2007. I also tried selecting the legacy mailbox backup. I am using a service account with an accessible and viewable mailbox. Note that when I backup the stores, I get 'access denied' when the mailbox options are selected. I have de-selected the mailbox options to see if that stops the job from being marked as failed. Any ideas? Thanks!