I imported Contacts into Outlook 2010 via a CSV file and the list of Contacts is fine. The Autocomplete cache however, is blank.

Using Nk2Edit, I have populated it using the 'Add from Address Book' function and although the cache is now fully populated with all Contacts, only some of them appear when I try Autocomplete in an email.

After some research online, I renamed the cache as OLD, let Outlook generate a new empty cache file, emailed someone and confirmed that the email address worked fine in Autocomplete and checked that it was the only entry in the new cache file. I then merged the OLD cache with the new one and had exactly the same symptoms. Only some of the cached Contacts appear in Autocomplete, although all Contacts are in the Address Book and in the Autocomplete cache file.

I have even run Scanpst on the PST file a couple of times, thinking it must be corrupted, but it did not fix the problem.

Having run out of ideas, I am hoping someone can help.

Thanks in advance