Almost never is the NK2 file corrupt. More likely, the profile is corrupt.
Did you try creating a new profile, then migrating the old NK2 file?
--
Russ Valentine
[MVP-Outlook]
"Gordon Prince, MCP" wrote in message
...
An Outlook 2003 user reported to me today that her nicknames stopped working
this morning. I found a utility that reads the contents of the .NK2 file
(nk2csv.exe from http://www.epute.com/nk2csv/) which shows there are a
couple of hundred names in the file. But typing part of a name doesn't
display the dropdown list of potential matches any more from Outlook.

I renamed the .NK2 file, restarted Outlook, sent an E-mail, closed Outlook
and there was a new .NK2 file, just like there is supposed to be. I replaced
it with the original file but only the names I've typed in today seem to
show up as prospective matches -- the couple of hundred old nicknames.

It seems like the .NK2 file is corrupt -- the names are there, but they
don't work. Is there a way to repair the corrupt file? Or does it just need
to rebuild a new .NK2 file as it gets used?