There are a few pieces of missing info with this problem description:
#1 - Outlook version?
#2 - Type of input data file (.CSV, .XLS etc)
However in the interests of time - generic answer without any other
information is:
Cause is more then likely a data problem within your input dataset. You
mention that some of your contacts are imported. Check to see the last
contact record imported (making sure that your view is not changing the
sequence in which these contacts are displayed otherwise locating the actual
"last" record may be a challenge) - find that contact within your input data
source and the most likely source of your problem will be the contact record
that immediately follows that one in the input dataset. If you can't readily
see the source of the problem - remove the contact and see how far you get
again.
Karl
__________________________________________
Karl Timmermans - The Claxton Group
ContactGenie - Importer 1.3 / DataPorter 2.0
"Power contact importers for MS Outlook '2000/2003"
http://www.contactgenie.com