Wrong members in outlook 2003 distribution list

I came upon a very strange case. The president of our company sent an email to a distribution list in outlook 2003 and the message was sent to members of another distribution list. The thing is that the first list he sent it to doesn't exist anymore in his contacts. But the email still was sent to another distribution list whose name starts the same as the first one.

I tried to send an email to the first list from his laptop and when I entered the first list name, outlook's auto-complete completed the distribution list's name even though it doesn't exist in the contacts anymore. Up to now, that is normal, that is one of the usage of the auto-complete function. But if I click on the plus sign beside the distribution list, it lists me the members of the other list that still exists in the contacts and whose name starts the same way as the other one.

I also tried to replicate the error on my laptop by creating a list (list A) with members A & B and then creating a list (list B) with members C & D. I sent emails to both lists (in seperate emails) and then deleted list A. When I tried sending an email to list A again, auto-complete showed me both choices (A & B) so I chose list A. But when I tried to expand list A, outlook told me that it doesn't exist anymore.

Please help because I could just delete the auto-complete entry for that missing list from the president's auto-complete file but I would rather know why it did that to avoid having other emails being sent to the wrong person.
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You can disable the Autocomplete by going to

Tools --> Options -->preferences--> email options -->advanced email options

suggest name while completing  blah halh   -- uncheck this , restart outlook
you can also get rid of the entire bad outlook cache file by deleting the .nk2 file from the users machine
LeRougeAuthor Commented:
I already know how to do that. You can also just delete the entry from the auto-complete by typing the beginning of the entry and when auto-complete suggests it, you just press delete and you are done. But the point of my question is to know why it did that and why I can't replicate that error on another machine.

Thanks but no thanks for the answers.

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