2003/Vista

I am on a network.  I used to have a DL in my contacts folder named ICA that
I deleted from my computer.  However, I have access to another co-worker's
contacts from which I access a DL with the same name (ICA).  When I bring up
a
new email and type "I" in the To box, I hit tab and ICA autofills into the
To box.  It appears that Outlook is recognizing her DL.  But I receive a
failure notice when I send the email, however, indicating that the DL is not
recognized.  My suspicion is Outlook is trying to connect it to the DL with
the same name that I deleted from my contacts folder.  When I right click the
ICA DL in my coworkers contacts folder and select New Message, there is never
a problem sending the message.  Explanations/Suggestions?