Importing into Accounts

[LostyJai]

When I try to import from a csv file into accounts, I get the error attached.

But if I ignore the error, the accounts are still created and they seem to look fine.
Can someone explain to me what the error is for?

[mnuding]

Can anybody shed some light onto this? I'm getting a similar issue, but it does seem to affect the result (for starters, I don't get the import feedback telling you about duplicates, etc... ). Somehow, some contacts make it into the database and some don't and I can't seem to figure out what factor qualifies them.

Help!