We have a user who is trying to use her Personal Address
Book to send an Excel spreadsheet while having Outlook
open at the same time.  She receives an error while in
Excel (and clicks File, Send To, Recipient (as
Attachment)) that her Personal Address Book is already
open by another computer, and she cannot access the PAB.  
This only occurs while her Outlook is open (on the same
computer).  Is there not a way to have Excel use the
instance of Outlook that is already open to send the
attachment?

Alternatively, I'd like to suggest that she import her
PAB into her Contacts in her Mailbox (we're on Exchange
5.5), but I think I recall an issue with Distribution
Lists in a PAB not being imported properly into the
Contacts.  Can you verify whether my memory serves me
correct?