After my most recent reinstall of windows, for some reason Outlook 2010 stopped looking in my Contacts when I would hit Check Names. It was only looking in the Global Address Book. I would have to look up the person in my contacts, and Outlook would autocomplete until it was restarted.
The solution is here: Outlook 2010: How to change your default Contacts Address Book
I changed mine to be custom so it would look in both the global address book (containing the employee list) AND my contacts. And it’s working.
Now to figure out why the autocomplete gets reset every time I close and reopen…