Importing from Excel to Outlook 2007

I’m having trouble. I’ve imported from excel to a contact folder in outlook a million times, but since we upgraded to Outlook 2007 it won’t work. It says it’s importing and then just an error message that it’s shutting down, do I want to send a report.
I’ve tried naming the ranges – this just leads to a message of too many fields named.
I’ve tried importing it as a csv file and that doesn’t work either. Same error as the first time.
Can anyone shed any light on this?